5. Management Strategy

Transcription

1 5. Management Strategy 5.1 Introduction The management strategy is developed to provide guidance for the future management of the TDSPSA and specifically to meet the goals and objectives within the context of future land use and other activities within the study area. The guidance provided, reflects the goals and objectives set for the area and the characteristics of the TDSPSA. Initially, the characterization (Section 3.0) was carried out in such a way as to identify current conditions related to the goals and objectives (e.g., characteristics of the natural environment including both terrestrial and aquatic, stream conditions, water quality, and hydrogeology) established for the area. The analysis (Section 4.0) focused on how the study area (including potential impacts related to land use change). Also examined were processes as they relate to the goals and objectives (e.g., Do current nutrient loadings to the stream lead to algae growth? Will urban land uses increase loadings? How can they be controlled if needed?). The subsequent steps involved in developing a management plan are presented in this section of the report and are as follows. Section 5.1 Section 5.2 Section 5.3 Provides an overview of the approach to developing a management strategy and the factors associated with the TDSPSA that led to the development of a management strategy. Provides a summary of issues (from the characterization and analysis portions of the Subwatershed Study) related to the goals and objectives that have led to the development of the strategy (e.g., Is management intervention needed?), and outlines what targets are needed to meet the specific objectives. Provides a detailed discussion of all of the management elements by component, how they have been selected, and why they are needed Description of a Management Strategy Many management strategy approaches are based on the carrying capacity of the subwatershed, as well as the goals and objectives set for the particular watershed. The application of the concept of carrying capacity requires an understanding of the limits of an ecosystem s ability to support various life forms and land use activities. In any watershed, the existing habitats are generally operating at carrying capacity under the existing pressures of the human matrix within which they lie. As human activities/pressures increase, the carrying capacity of the habitats is reduced. The concept of carrying capacity is generally translated in watershed management into identifying a threshold beyond which the reduction in carrying capacity is not acceptable. In many traditional watershed studies this threshold is based on the survival of key indicator species or habitat types, usually rare species or sensitive habitats that are also protected by policies and regulations. Human activities are then managed in a way that does not exceed the natural limits that would result in unacceptable negative impacts to key indicator species or habitats. (tremaine_dundas subwatershed study september_2009.doc)

2 In this study a systems approach was used to develop a management strategy that identified a NHS consistent with current direction of the Provincial Policy Statement Instead of focusing on the identification of thresholds to sustain certain significant species and/or habitats, the goal of a systems approach is to manage sustainably the full range of species (i.e. biodiversity) and habitats currently present within an ecologically linked system of protected habitats, which collectively is referred to as a NHS. The protection of fully functioning ecosystems provides the best long term protection of the many significant plants and animals recorded within the TDSTSA and the significant wildlife habitats that sustain them within the TDSPSA. The objectives of a systems approach are to maintain and protect: Ecological features in the environment such as woodlands, wetlands, and watercourses; Ecological functions of the environment such as water storage and water quality enhancement by wetlands, winter deeryards provided by dense cedar woodlands, and amphibian breeding habitat in ephemeral forest ponds; and Ecological interactions that occur over varying scales of time and space such as animal predation and herbivory, the daily, seasonal and long-term movement patterns of plants and animals, and the role of ecological disturbance mechanisms such as fire, wind, water, and disease. The management strategy must recognize that human activities will continue, and that land use activities and changes are also a part of society s requirements. It is important that the management strategy is based on protecting a sustainable NHS that can withstand the impact of future land use changes and that feasible and practical rehabilitation measures are used to enhance conditions and manage expected changes. These enhancements should result in improved resiliency of the system and overall health of the watershed. The scope of a management strategy must be broad enough to include all of the technical and administrative tools that are involved in land use and resource management measures. The scope of the strategy includes: Land Use Management Measures That guide land use in a manner that recognizes the natural environment which includes terrestrial resources, wildlife, wildlife habitat, ecological linkages and associated environmental corridors, stream and riparian corridors, and the subwatershed processes that influence these resources; SWM Measures To preserve or enhance hydrologic functions/flow conditions related to surface water and groundwater flows and water quality; Terrestrial and Wetland Resource Management To protect and enhance terrestrial and wetland resources; Riparian Corridor Management Plans To protect and enhance riparian systems; Rehabilitation and Remediation Plans For environmental (terrestrial and aquatic) features to increase the resiliency of the catchments and stream system; Monitoring Plan Must be practical and focused to measure the environmental health of the catchments and to track the effectiveness of the management strategy (Section 6.0); Implementation Plan Must describe how the subwatershed management strategy is to be put into place. Based on the mandates of the various agencies and stakeholders, identify the specific roles and responsibilities for each group (Section 6.0); and (tremaine_dundas subwatershed study september_2009.doc)

3 Contingency Plan If needed, this plan provides modifications to the strategy if objectives or targets change. The contingency plan allows for the implementation of the AEM approach. 5.2 Actual Subwatershed Goals, Objectives and Targets A subwatershed management strategy is developed on the basis of the goals and objectives for the TDSPSA which were introduced in Section These objectives were used to guide the overall characterization of the catchments and the analysis carried out and the development of this management strategy, which are refined and in Section 5.2. In addition, the strategy also reflects the input by the Secondary Planning process. In this way the strategy that has been developed shows consideration for the three cornerstones of subwatershed planning: environmental objectives, social concerns, and economic considerations. For this study, the following steps led to the development of this management strategy: Goals and objectives were established resulting in the identification of the key subwatershed components or areas to be considered; Concerns and issues were identified; The information collected was analyzed, resulting in the development of a series of targets related to specific goals and objectives; The targets were used to develop a management approach and strategy. By setting targets within the strategy, the effectiveness of the approach and strategy can be monitored and evaluated; and The management approach includes monitoring and contingency plans that help determine whether targets are being met, and assists in modifying the strategy to help achieve the identified goals and objectives. This section provides a summary of the management issues identified through the characterization and analysis phases of this Subwatershed Study (Sections 1.0 through 4.0), for each goal and objective. The targets related to these goals and objectives are then discussed and the management issues are presented. The overall goals, objectives, management issues, and targets are summarized in Table 5.2.1, and described in more detail In Section Goal #1 To minimize the threat to life and the destruction of property and natural resources from flooding, erosion and unstable soils, and preserve (or re-establish, where possible) natural floodplain hydrologic and fluvial geomorphologic functions Goal #1, Objective 1.1 To adopt appropriate land use controls and development standards to prevent development in natural flood hazard and erosion hazard areas. (tremaine_dundas subwatershed study september_2009.doc)

4 In order to protect existing and future development from flood potential, the floodlines that have been developed are used to delineate flood hazard lands. All development is to be excluded from within the Regional Storm or 1:100-year floodplain, whichever is greater. In areas where floodplains are not delineated, conveyance for flood events, (i.e., the greater of the Regional Storm or the 1:100-year storm) is to be provided for in the conveyance system, in accordance with City of Burlington drainage standards. Stream Corridor (meander belt width, access allowance, and erosion setback) Erosion hazards exist primarily through channel migration and the resultant loss of property. In the case of a defined valley setting, this migration may result in toe erosion, causing a decrease in slope stability and subsequent failure of the valley wall. In order to address these concerns, stream corridors were identified for the study area on a reach basis. These corridors are meant to incorporate the meander belt width for each reach plus an additional factor of safety and m setback which includes a 6 m erosion access allowance. These requirements are consistent with the Provincial Policy Statement (2005) and Conservation Halton Guidelines. Due to the study approach, a detailed meander belt width and hazard assessment was not completed on a reach basis. As such, the values presented in this report are conservative approximations and should be refined based on more detailed studies in the EIR stage and detailed geomorphic in the detailed site plan stage in order to establish the hazard limits associated with each watercourse. For not apparent/unconfined valley systems, the area potentially subject to erosion is considered to be the meander belt plus appropriate factor of safety (to account for long term erosion/channel migration). For apparent/confined valley systems, the area potentially subject to erosion has traditionally been considered to be delineated by the location of the stable top of bank (or stable top of valley slope). Where the existing slope inclination is stable and the slope is not susceptible to toe erosion (over a 100 year planning horizon), the physical top of bank is considered to be the stable top of bank. Where the slope inclination is not stable or where the toe of slope is potentially susceptible to toe erosion, the location of the stable top of bank is established through the appropriate fluvial geomorphological and geotechnical technical analysis. In additional, a meander belt width (plus factor of safety) should also be applied. This will enable the work to be consistent with the North Oakville Creeks Subwatershed Study, which would also provide a more comprehensive evaluation of the risks associated with channel erosion and channel migration. All development should be setback from the flooding hazard (greater of the Regional Storm and 100-year floodplain) to provide a factor of safety, to allow for unforeseen external events, and to provide for access/egress outside of the flooding hazard. The targets should state specific setbacks for the subwatershed, namely 7.5 m from the greatest hazard associated with minor watercourse systems (Fourteen Mile Creek) and 15 m from the greatest hazard associated with major watercourse systems (Bronte Creek). Targets Delineate floodplains to provide development limits. Restrict development in the floodplains as per Provincial and Conservation Authority policies. (tremaine_dundas subwatershed study september_2009.doc)

5 Restrict development in wetlands as per provincial and Conservation Authority Policies. Delineate meander belt width and associated setbacks to be applied on all streams designated to be left as an open watercourse (providing erosion protection). Apply valley wall setback standard (stable slope top of bank plus setbacks). A 7.5 m (minor systems) or a 15 m (for major systems) setback, as per Conservation Halton policies to be applied from the greater of the various hazards limits Goal #1, Objective 1.2 To ensure that runoff from developing and urbanizing areas is controlled such that it does not increase the frequency and intensity of flooding at the risk of threatening life and property, and to provide erosion control. Minimize the diversion of flows between subwatersheds and subcatchment areas to protect flow regime corridors in the receiving systems. (tremaine_dundas subwatershed study september_2009.doc)

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7 Table Summary of Goals, Objectives and Targets Goals Objectives Targets Goal #1 To minimize the threat to life and the destruction of property and natural resources from flooding, erosion and unstable soils, and preserve (or re-establish, where possible) natural floodplain hydrologic and fluvial geomorphologic functions. Goal #2 To restore, protect, and enhance water quality and associated aquatic resources and water supplies for watercourses, including their associated hydrologic and hydrogeologic functions within the subwatershed areas. Objective 1.1 To adopt appropriate land use controls and development standards to prevent development in natural flood hazard and erosion hazard areas. Objective 1.2 To ensure that runoff from developing and urbanizing areas is controlled such that it does not increase the frequency and intensity of flooding at the risk of threatening life and property, and to provide erosion control. Minimize the diversion of flows between subwatersheds and subcatchment areas to protect flow regime corridors in the receiving systems. Objective 2.1 Protect stream morphological and fluvial character; restore, where appropriate and feasible, sinuosity; maintain physical habitat attributes (e.g., pools and riffles), diversity and fluvial processes (e.g., bedload transport and energy reduction through sinuosity); and prevent increase in erosion and deposition, through maintenance of hydrological regime. Delineate floodplains to provide development limits. Restrict development in the floodplains as per Provincial and Conservation Authority policies. Restrict development in wetlands as per provincial and Conservation Authority Policies. Delineate meander belt width and associated setbacks to be applied on all streams designated to be left as an open watercourse (providing erosion protection). Apply valley wall setback standard (stable slope top of bank plus setbacks). A 7.5 m (minor systems) or a 15 m (for major systems) setback, as per Conservation Halton policies to be applied from the greater of the various hazards limits. Develop SWM plan to replicate flow-frequency-duration from existing conditions. Maintain existing peak discharge rates for all design events, particularly high flows. Target discharge rates required for each subwatershed (unit area). Meet threshold tractive force targets. Minimize diversion of subwatershed areas to protect flow regime in receiving systems Maintain existing floodplain storage characteristics within the stream system. Preserve the stream network required to preserve function of stream network from a geomorphologic perspective. Meander belt targets to protect streams morphologic character. Identify stream corridors for protection. Threshold targets set by subwatershed to provide for flow regime target. (tremaine_dundas subwatershed study september_2009.doc)

8 Goals Objectives Targets Objective 2.2 To prevent the accelerated enrichment of streams, thermal pollution, and contamination of waterways from runoff containing sediment, nutrients, pathogenic organisms, organic substances, and heavy metals and toxic substances. Where possible, provide water quality control through appropriate Best Management Practices on the land. Objective 2.3 To maintain or restore a natural vegetative canopy along streams where required to ensure that mid-summer stream temperatures do not exceed tolerance limits of desirable aquatic organisms. Objective 2.4 To ensure that hydrogeologic function is preserved and maintained and take full advantage of stream and groundwater discharge/baseflow enhancement opportunities. Objective 2.5 To ensure no net loss of productive capacity of the existing fish habitat occurs, and incorporate enhancement, where possible. Objective 2.6 To minimize disturbance of wetlands, preserving and/or enhancing the habitat and functions they provide. Targets will vary depending upon subwatershed (fishery condition for some items). Phosphorus An overall target of no increase in loading after development is proposed based on protection of the Lake Ontario shoreline. Suspended Solids SWM ponds are recommended to be designed for an enhanced level of protection requiring 80% removal of TSS for all receiving streams. Chloride No specific target recommended, but the Halton Region and City of Burlington should update their Salt Management Plan to reflect requirements in the Canada Gazette Road Salt Code of Practice (April 2004), especially with respect to the application of Environmental Impact Indicators for road salt and identification of areas vulnerable to road salt effects. Dissolved Oxygen PWQOs for cold and warmwater fisheries. Provide an enhanced level of SWM control to provide an appropriate level protection in receiving watercourses. Maintain existing riparian vegetation associated with watercourses where feasible. Active restoration of riparian zones with native plantings, in cases where watercourse modifications/alterations require permitting/authorization. Develop approaches that maximize infiltration using best efforts and best available technology (i.e., most practical, feasible, sustainable, and cost effective) to continue the existing recharge/discharge function. Considering the available water surplus and soil conditions at the site, the infiltration target of a minimum of 86,200 m3/yr can be considered. This value would be applicable to the entire study area, including all land uses combined. Protect areas of potential groundwater discharge through preservation of associated streams. The targets relating to biodiversity for Bronte Creek and the north-eastern Fourteen Mile Creek tributary should ensure that the diversity of the fish community be maintained at existing levels, at a minimum, and increased if possible. Identify stream corridors for protection. Preserve the stream network required to preserve function of stream network from a geomorphologic perspective. Meander belt targets specified to provide for natural meander. Threshold targets set by subwatershed to provide for flow regime target. Meet or exceed established Provincial Water Quality Targets. Retain wetlands within stream corridors if possible, and incorporate into drainage system. Avoid installation of barriers to fish passage. Maintain ecological linkages between wetland and woodland areas. Maintain the function of all wetlands associated with watercourses. Maintain the function and structure of wetlands within woodlands. Objective 2.7 Establish appropriate feature-specific buffers for protection of natural habitats. (tremaine_dundas subwatershed study september_2009.doc)

9 Goals Objectives Targets Goal # 3 To restore, protect, develop, and enhance the Natural Heritage, historic, cultural, recreational, and visual amenities of rural and urban stream corridors. Provide appropriate buffers to wetlands, watercourses, and valley lands to maintain or enhance their biological health and meet objectives of long-term sustainability of these features. Objective 3.1 To ensure that new development incorporates the most appropriate development form and mitigation measures necessary to optimize compatibility with natural features and their associated functions. Objective 3.2 To ensure that environmental resource constraints are fully considered in establishing land use patterns in the TDSPSA. Objective 3.3 To ensure that existing wildlife linkages are preserved and that opportunities for improving these linkages are considered/implemented as part of any future development. Objective 3.4 To ensure that development in the stream corridor is consistent with the historical and cultural character of the surroundings and reflects the need to protect visual amenities. Objective 3.5 To ensure that the recreational and fisheries potential of a watercourse are developed to the fullest extent practicable. Buffers to conform to existing Greenbelt, 2005 PPS and ROP policies and Conservation Halton regulatory and planning policies Aquatic protection based upon resident fish community and existing aquatic habitat conditions. Achieve MOE enhanced level of SWM protection (80% TSS removal) for all reaches supporting redside dace populations (Fourteen Mile Creek). For all other stream reaches, achieve a normal level of SWM protection (70% TSS removal) to adequately protect aquatic habitat and resident fish. Note that enhanced protection of these streams may be required for reasons not directly related to aquatic habitat and resident fish. (See Section 4.6 regarding Phosphorus loadings). Enhanced level of SWM protection for any stormwater being directed into the Bronte Creek system due to a sensitive and valuable fish community within this catchment. See targets listed for wetlands, woodlands, and other vegetation community types; Provide for linkages; and Provide buffers. Maintain ecological linkages associated with tributaries of Fourteen Mile Creek. Maintain ecological linkages between upland woodlands and the adjacent natural areas of the Bronte Creek valley. Where a road crossing is unavoidable potential impacts to wildlife movement should be considered and minimized by implementing mitigation measures such as, minimizing the length of the crossing, utilizing special road design (width, boulevard, traffic calming, signage, wildlife crossings, etc.) to enhace wildlife movement opportunities and reduce the threat to wildlife movement; and Maintain the regional ecological linkages within and beyond the TDSPSA provided by natural areas along the Bronte Creek valley. Presence of visual and historic amenities through the subwatershed and Secondary Planning Processes. See discussion under Objectives 3.1 and 2.3 (tremaine_dundas subwatershed study september_2009.doc)

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11 Flood Protection Flood protection goals include protecting the public and property from flood damages that could result from increased runoff rates and volumes due to new development. The study analysis has demonstrated that flows will increase without appropriate controls. Also, downstream riparian landowners have the right to receive runoff quantity and quality in the current state. The targets will maintain runoff peak flow rates from new development to existing levels for the 2-year through 100-year return periods and the Regional Storm. Targets Develop SWM plan to replicate flow-frequency-duration from existing conditions. Maintain existing peak discharge rates for all design events, particularly high flows. Target discharge rates required for each subwatershed (unit area). Meet threshold tractive force targets. Minimize diversion of subwatershed areas to protect flow regime in receiving systems. Maintain existing floodplain storage characteristics within the stream system Goal #2 To restore, protect, and enhance water quality and associated aquatic resources and water supplies for watercourses, including their associated hydrologic and hydrogeologic functions within the subwatershed areas Goal #2, Objective 2.1 Protect stream morphological and fluvial character; restore, where appropriate and feasible, sinuosity; maintain physical habitat attributes (e.g., pools and riffles), diversity and fluvial processes (e.g., bedload transport and energy reduction through sinuosity); and prevent increase in erosion and deposition, through maintenance of hydrological regime. To achieve this objective, morphological targets were established on a reach basis in the form of an overall geomorphic classification, which dictates the management approach for the stream network. The overall geomorphic classification identified three categories of streams according to their relative sensitivity, rehabilitation potential, and geomorphic form and function. These three categories included: Streams that displayed a high sensitivity to change and have a well developed geomorphic form and function; Streams that exhibited some sensitivity to change and geomorphic function with a moderate degree of form; and Streams that lacked a defined form but still had a geomorphic function such as sediment transport, flow conveyance, and connectivity to other features. (tremaine_dundas subwatershed study september_2009.doc)

12 In order to prevent an increase in erosion and deposition within the study area, erosion threshold targets were developed to determine critical discharge for bed materials across the stream network. Furthermore, rehabilitation of existing reaches will restore morphology, increase diversity, and provide greater capacity to handle flows. These targets will provide guidance for the study area SWM measures by outlining flow regime objectives. Targets Preserve the stream network required to preserve function of stream network from a geomorphologic perspective. Meander belt targets to protect streams morphologic character. Identify stream corridors for protection. Threshold targets set by subwatershed to provide for flow regime target Goal #2, Objective 2.2 To prevent the accelerated enrichment of streams, thermal pollution, and contamination of waterways from runoff containing sediment, nutrients, pathogenic organisms, organic substances, and heavy metals and toxic substances. Where possible, provide water quality control through appropriate Best Management Practices on the land. Analysis carried out on existing conditions resulted in the identification of concerns regarding potential surface water quality impacts and the need for mitigation through the management strategy. Mitigation measures will be required which addresses the potential water quality impact. These included: Current nutrient levels in the streams, the potential increases in nutrients, and associated impacts on algae growth; The potential increase in suspended solids and associated urban pollutants; The level of chloride and potential increase; and The need to manage stream temperature for fisheries protection. The management needs resulted in the selection of phosphorus, suspended solids, chloride, and temperature as the representative parameters for management targets and monitoring. The selection of these parameters as a basis for targets was discussed in Section 4.6 Analysis of Water Quality Impacts. The MOE (1994) provides a listing of PWQOs that apply to surface waters, including those in the TDSPSA. The PWQOs are numerical and narrative criteria which serve as chemical and physical indicators representing a satisfactory level for surface waters (i.e., lakes and rivers) and, where it discharges to the surface, the groundwater of the province. The PWQO are set at a level of water quality which is protective of all forms of aquatic life and all aspects of the aquatic life cycles during indefinite exposure to the water. It is considered that the PWQOs apply to all the watersheds and that monitoring be continued for parameters not specifically identified as targets for this study. No specific target is (tremaine_dundas subwatershed study september_2009.doc)

13 adopted for other parameters such as heavy metals. Use of TSS as a control parameter for design of SWM measures will result in a high level of control for contaminants associated with TSS, such as metals. Aquatic Biota For streams which support redside dace and/or silver shiner, removal of suspended solids is considered important. Redside dace and silver shiner are sight feeders and as such require relatively clear, not turbid water to forage effectively. Accordingly a target of enhanced (80% TSS removal) level of SWM protection (as per MOE guidelines) for Bronte Creek and the north-eastern Fourteen Mile Creek tributary will ensure that the maximum benefit of available and affordable SWM technologies are provided to these streams. Targets Targets will vary depending upon subwatershed (fishery condition for some items). Phosphorus An overall target of no increase in loading after development is proposed based on protection of the Lake Ontario shoreline. Suspended Solids SWM ponds are recommended to be designed for an enhanced level of protection requiring 80% removal of TSS for all receiving streams. Chloride No specific target recommended, but the Halton Region and City of Burlington should update their Salt Management Plan to reflect requirements in the Canada Gazette Road Salt Code of Practice (April 2004), especially with respect to the application of Environmental Impact Indicators for road salt and identification of areas vulnerable to road salt effects. Dissolved Oxygen PWQOs for cold and warmwater fisheries. Provide an enhanced level of SWM control to provide an appropriate level protection in receiving watercourses Goal #2, Objective 2.3 To maintain or restore a natural vegetative canopy along streams where required to ensure that mid-summer stream temperatures do not exceed tolerance limits of desirable aquatic organisms. Some watercourses within the study area have had riparian vegetation impacted to some degree by agricultural activities. The degree of impact varies from watercourse to watercourse, and within watercourses by reach. Levels of impact range from the complete removal of vegetation, a reduction of the riparian vegetation to a narrow strip, or areas where the riparian corridor remains very much intact within a larger woodlot or wetland feature. The protection of designated floodplain and meander belt width will have positive implications for the thermal regime of the watercourses as vegetative succession occurs in these zones. In addition, these zones will positively influence other factors associated with aquatic habitat maintenance and enhancement. The vegetative buffers afforded by these zones limits the potential for impacts from (tremaine_dundas subwatershed study september_2009.doc)

14 human-dominated land uses on the stream channel, compared to the current conditions. These zones can also act as filters, effectively removing suspended sediment, often contained in overland urban flow, and stopping it before it enters the watercourses and negatively influencing aquatic communities. Depending on the stream geometry and/or hydrology/hydraulics, it is expected that riparian zones of a minimum of 20 m in width and a maximum of over 100 m in some cases will be established. Based on analysis of stream morphology (see Section 4.7) the recommended minimum riparian protection zones for the TDSPSA vary from a minimum of 39 m in width to a maximum of 210 m (see Table 4.7.2). Provided that riparian cover can be maintained and or re-established in these zones, adequate riparian vegetative canopy to moderate stream temperatures is expected to develop. In essence, the establishment of riparian canopy will occur as a result of management for fluvial and floodplain aspects of these watercourses. Given that these zones will exist, the target for vegetative enhancement is dictated by the extent to which intervention should occur as part of the permitting process to accelerate vegetative succession. For habitats that have been identified as critical aquatic habitats, active planting may be used to accelerate riparian growth and associated temperature moderation. The exception is for redside dace habitat, where herbaceous grass cover is preferred over woody riparian vegetation. Redside dace are known to be closely associated with this habitat type (Parish, 2004) and temperature does not appear to be a controlling factor. It would appear that the benefit provided by insects (food base) growing in this type of vegetation is more important than the temperature moderation offered by woody vegetation. For habitats that have been designated as important or marginal aquatic habitat, establishing the fluvial/floodplain limits and then either letting vegetative succession proceed without intervention or rehabilitating the stream and its riparian corridor for enhancements is warranted. Environment Canada (2001) recommended that streams having 75% of their length surrounded by natural vegetation were usually healthy, especially if the width of the vegetation was greater than 30 m. Targets Maintain existing riparian vegetation associated with watercourses where feasible. Active restoration of riparian zones with native plantings, in cases where watercourse modifications/alterations require permitting/authorization Goal #2, Objective 2.4 To ensure that hydrogeologic function is preserved and maintained and take full advantage of stream and groundwater discharge/baseflow enhancement opportunities. Groundwater Surface Water Interaction Maintaining the relationship between the groundwater system and the surface water system is the focus of this objective. This can be done, in part, by managing infiltration which assists in sustaining groundwater discharge to surface water features and the elevation of the water table. (tremaine_dundas subwatershed study september_2009.doc)

15 Groundwater discharge zones are often found immediately adjacent to the watercourses, usually within the floodplain or riparian corridor associated with watercourses. In addition, groundwater is being used to some degree by local residents as a drinking water supply source. As such, the local use of groundwater as a potable water supply source must be considered until alternatives are readily available. As a result, the specific objectives related to hydrogeology include: Maintaining groundwater supplies for existing residents while development and servicing proceed. Keeping changes in the depth to the local water table to within the seasonal fluctuations normally experienced. Maintaining the groundwater contribution to stream health (groundwater quantity and quality). Since groundwater withdrawal from the subsurface in the future will not affect either groundwater supplies or the contribution of groundwater to streamflow, the targets for hydrogeology focus on the input of water to the subsurface (i.e., infiltration and recharge). Accordingly targets must focus on maintaining sufficient infiltration so that current recharge/discharge processes are continued. Recognizing the difficulty presented by ground conditions in the area, primarily the low hydraulic conductivity of local surficial soils, best management practices must be used to ensure that as much water as possible is made available for infiltration purposes. Targets Develop approaches that maximize infiltration using best efforts and best available technology (i.e., most practical, feasible, sustainable, and cost effective) to continue the existing recharge/discharge function. Considering the available water surplus and soil conditions at the site, the infiltration target of a minimum of 20,500 m 3 /yr can be considered. This value would be applicable to the entire study area, including all land uses combined. Protect areas of potential groundwater discharge through preservation of associated streams Goal #2, Objective 2.5 To ensure no net loss of productive capacity of the existing fish habitat occurs, and incorporate enhancement, where possible. Biodiversity is a measure of the number of species present in an ecosystem as well as the distribution of individuals among species. As ecosystem health improves, new and improved habitats can be expected to lead to an increase in the biodiversity of aquatic life. The management approach to stream corridors for this study will ensure protection of the stream channel, as well as a vegetative buffer along the corridors. The re-establishment of vegetation along the stream channels, and in some cases the maintenance and improvement of stream geometry, is expected to result in improved habitat conditions and ultimately improved biodiversity. This includes consideration of existing wetlands associated with stream channels and riparian zones. (tremaine_dundas subwatershed study september_2009.doc)

16 The diversity of the fish communities in Bronte Creek and Fourteen Mile Creek are quite good. A review of data collected from all available sources reveals that Bronte Creek supports at least 44 species of fish within its lower reaches (Conservation Halton, 2002). Fourteen Mile Creek supports at least 17 species of fish (TSH et al., 2006a; Philips, 2002; MNR, 2003). The targets relating to biodiversity for these watercourses should be to ensure that diversity of the fish community be maintained at existing levels, at a minimum, and increased if possible. Water quality control and improvement is considered important for certain aquatic habitats (see Objective 2.2 for additional detail). Barriers to fish passage, whether intentional or not, limit the productive capacity of a watercourse. Access to suitable spawning habitat may be restricted, reducing recruitment. Targets The targets relating to biodiversity for Bronte Creek and the north-eastern Fourteen Mile Creek tributary should ensure that the diversity of the fish community be maintained at existing levels, at a minimum, and increased if possible. Identify stream corridors for protection. Preserve the stream network required to preserve function of stream network from a geomorphologic perspective. Meander belt targets specified to provide for natural meander. Threshold targets set by subwatershed to provide for flow regime target. Meet or exceed established Provincial Water Quality Targets. Retain wetlands within stream corridors if possible, and incorporate into drainage system. Avoid installation of barriers to fish passage Goal #2, Objective 2.6 To minimize disturbance of wetlands, preserving and/or enhancing the habitat and functions they provide. The goal of protecting wetlands within the TDSPSA is to maintain and enhance the existing wetland features and functions. A number of numeric thresholds have been cited in the literature with respect to wetlands. For example, Environment Canada recommends that at least 10% of watersheds should be comprised of wetlands, especially wooded swamps and a variety of marshes (Environment Canada, 2002; 2004). Wetlands in the TDSPSA consist of: Treed Swamp Wetland Located within a bottomland area along Bronte Creek sustained through a combination of seasonal flooding and high water table. Swamp thicket and Floating Leaved Aquatic Wetlands Associated with the pond present within (tremaine_dundas subwatershed study september_2009.doc)

17 the TDSPSA. The pond was created through past aggregate extraction and the creation of berm which detain surface water runoff. The pond and associated wetland provide important wildlife habitat and have important ecological linkage connections to adjacent woodland areas. Meadow Marsh Wetlands Associated with watercourses of Fourteen Mile Creek present within the study area. These wetlands are generally online features that have been established as a result of flow patterns in the channels (e.g., low gradient systems and areas with impeded flows). These wetlands filter and detain surface water runoff thereby contributing to water quality and quantity. Targets Maintain ecological linkages between wetland and woodland areas. Maintain the function of all wetlands associated with watercourses. Maintain the function and structure of wetlands within woodlands Goal #2, Objective 2.7 Provide appropriate buffers to wetlands, watercourses, and valley lands to maintain or enhance their biological health and meet objectives of long-term sustainability of these features. Although not specifically mentioned in the original objective, buffers from woodlands are also discussed here. The identification of buffers around wetlands and woodlands has received considerable research in the recent past. There are a number of similarities in the approaches typically used to delineate these buffers. From a review of numerous past studies on buffers, general components/approaches have been used to identify the extent of buffers: Cases where the immediate protection of the edge of the natural habitat is considered. For example, buffers for the protection of wetland vegetation and control of runoff to wetlands. These dimensions are typically smaller. A dimension of 30 m is in common usage for PSWs (Environment Canada, 2004; Ministry of Municipal Affairs and Housing, 2005). In some cases the protection of woodlands considers arboricultural approaches in which the focus is on the physical protection of the outer trees based on root zone protection. This type of approach results in a modest buffer normally in the range of 5 to 10 m from the dripline. However in the case of hazard prevention some outer tier trees may be over 25 m tall, suggesting buffers of this dimension or greater. A number of recent studies have identified substantial buffers around natural habitats based on specific species habitat requirements. In some cases the extent of buffers takes into account the relationship of neighbouring open vegetation types as possible foraging and/or movement habitats for wildlife that use the woodlands. This is generally determined on a site specific basis and considers the presence of pockets of habitats retained within as well as outside the woodland or wetland. To improve and protect water quality and aquatic habitat and to achieve federal watershed health guidelines. A minimum 30 m vegetated riparian zone is recommended wherever possible. (tremaine_dundas subwatershed study september_2009.doc)

18 The targets associated with buffers are based on the overall objectives of maintaining the biodiversity of the habitats in the area. The identification and use of appropriate buffers and consideration of edge effects and the ecological needs of species within the natural areas is recommended. Targets Establish appropriate feature-specific buffers for protection of natural habitats. Buffers to conform to existing Greenbelt, 2005 PPS and ROP policies and Conservation Halton regulatory and planning policies Goal #3 To restore, protect, develop, and enhance the Natural Heritage, historic, cultural, recreational, and visual amenities of rural and urban stream corridors Goal #3, Objective 3.1 To ensure that new development incorporates the most appropriate development form and mitigation measures necessary to optimize compatibility with natural features and their associated functions. Terrestrial and Wetland From a terrestrial perspective, this objective of the Subwatershed Study focuses on the protection of important woodlands, wetlands and open habitat vegetation communities both in terms of their ecological structure and function. Of particular importance is the protection of significant plant species present within the TDSPSA, such as the endangered tree butternut and the 19 plant species considered rare or uncommon in Halton region (see Appendix B-1). Specific detailed discussion relative to wetlands is included above. The consideration of these features includes several aspects: The structure, function and conservation of vegetation communities of conservation concern (see further discussion under Objectives 2.6 and 3.2); The presence of plant species of conservation concern (including rare species) (see further discussion under Objectives 2.6 and 3.2); The provision of wildlife habitats (see further discussion under Objectives 2.6, 3.2 and 3.3); Ecological linkage opportunities (see further discussion under Objective 3.3); The influence of vegetative cover on aquatic habitats (see further discussion under Objective 2.3), and The relationship of vegetative cover and type on hydrologic aspects of the TDSPSA (see further discussion under Objectives 2.1 to 2.4). (tremaine_dundas subwatershed study september_2009.doc)

19 Aquatic Maintenance of a healthy aquatic ecosystem requires that predevelopment flows be maintained or enhanced to a level within the fluvial capacity of the streams. There are two main components that contribute to streamflow, surface runoff and infiltration, followed by groundwater discharge. In addition there may be groundwater discharge from deeper zones such as layers or lenses in the overburden or the shallow bedrock. In an urban setting, surface runoff is collected by a SWM system, treated and discharged. The method of SWM treatment can have considerable impact on the quality and quantity of the waters being discharged, as well as the timing of these discharges in relation to the natural setting. Land development can alter infiltration volumes which may affect subsurface flows and discharges to streams. Therefore, consideration of the degree to which surfaces are hardened is necessary since diverting too much infiltration flow to a surface treatment system can impact fish and fish habitat by changing the hydrograph of the watercourse. Targets Aquatic protection based upon resident fish community and existing aquatic habitat conditions. Achieve MOE enhanced level of SWM protection (80% TSS removal) for all reaches supporting redside dace populations (Fourteen Mile Creek). For all other stream reaches, achieve a normal level of SWM protection (70% TSS removal) to adequately protect aquatic habitat and resident fish. Note that enhanced protection of these streams may be required for reasons not directly related to aquatic habitat and resident fish. (See Section 4.6 regarding Phosphorus loadings). Enhanced level of SWM protection for any stormwater being directed into the Bronte Creek system due to a sensitive and valuable fish community within this catchment. Restricting development in, and adjacent to, wetlands Goal #3, Objective 3.2 To ensure that environmental resource constraints are fully considered in establishing land use patterns in the TDSPSA. From a terrestrial perspective, this objective of the Subwatershed Study focuses on the protection of important woodlands, wetlands and open habitat vegetation communities both in terms of their ecological structure and function. Of particular importance is the protection of significant plant species present within the TDSPSA, such as the endangered tree butternut and the 19 plant species considered rare or uncommon in Halton region (see Appendix B-1). Specific detailed discussion relative to wetlands is included above. Woodlands Relatively large, contiguous woodland areas are present in association with the Bronte Creek valley, including areas of interior woodland. A large woodland patch is also present within the tableland area (tremaine_dundas subwatershed study september_2009.doc)

20 currently dominated by agricultural land use. Based on the character of the woodland features present within the TDSPSA, the following targets were identified: Minimize the fragmentation of woodlands; Maintain the function of all woodlands that are >200 m in width (i.e., provide potential interior conditions); Roads should be located outside the NHS where possible, where a road crossing is unavoidable the length of the crossing should be minimized, the area crossed selected to minimize impacts to features and special road design (width, boulevard, traffic calming, signage, wildlife crossings, etc.) implemented to reduce environmental impacts; and Maintain the function of woodlands associated with the Bronte Creek valley. Hedgerows Well developed hedgerows dominated by long-lived native hardwood species are present within the areas of agricultural land use. These hedgerows provide ecological linkages from the tableland woodland to the Bronte Creek valley. Based on the quality and species of trees present within some hedgerows within the TDSPSA, the following targets were identified: Maintain to the maximum extent possible the features and functions of those hedgerows identified as significant and protect healthy, native trees within other hedgerows where possible. Wetlands The goal of preserving wetlands within the study area is discussed in Objective 2.6. Open Habitat - Vegetation Communities Open habitats provide habitat for unique suite of wildlife, and open habitat may play an important supporting role for woodlands and wetlands. As discussed in Section these areas were found to provide a number of functions and features of note. This includes the provision of habitat for species of conservation/management concern (including rare species), a role as foraging/nesting habitat for species associated with woodlands and wetlands, as well as a possible linkage role. These types of vegetation communities are often not specifically targeted for management or inclusion in NHS in subwatershed or planning studies. In increasingly developed landscapes, it is important to maintain habitat for all species. Natural grasslands in southern Ontario have largely been lost to agriculture and afforestation. Restoration of grasslands or maintenance of other open habitats at virtually any scale can provide habitat for grassland flora. Providing habitat for grassland fauna is more challenging. Efforts on a regional scale to provide a greater number of smaller patches of differing habitat structure in conjunction with at least one larger patch should be pursued to maintain or increase numbers of grassland birds. In the increasingly (tremaine_dundas subwatershed study september_2009.doc)

21 fragmented landscape of the study area, open habitat of varying sizes and vegetation structure will help to sustain populations of grassland birds. Recognizing the relationship of these habitat types to wetlands, woodlands, and stream corridors, and the provision of habitat for the species of conservation/management concern, the following targets are recommended: Maintenance of early successional stands in locations where they are found associated with existing wetlands, woodlands, and watercourses; Protection or creation of these habitat types (through natural succession) in large, strategically located blocks; and Minimize fragmentation of open habitats. Wildlife The goals for protection of flora and fauna species, particularly significant wildlife habitat, overlap with those noted above for wetlands, woodlands, and other habitat types. The key objective for flora and fauna is the preservation of biodiversity. Given the character of the habitats and species known from the TDSPSA, and relationship of these habitats to others outside the study area, the management of flora and fauna species must be considered at the metapopulation level. This translates to considering the specific habitat patches, as well as linkages between these habitats and beyond the limits of the study area. Many wildlife species use a range of habitat types for different aspects of their life history, and this range of habitats must be considered. For example, protection of forest interior stands (as discussed above) speaks to the nesting needs of certain sensitive forest interior species, but in many cases species forage and move outside these forested stands through other vegetation community types (see Wegner and Merriam, 1979). Amphibians provide a prime example on why metapopulations must be managed. Depending on their life cycle stage and season, amphibians require different habitats. Spring peepers (Pseudacris crucifer), for example, use marsh habitats for breeding, but then migrate to upland areas once breeding is complete or once tadpoles have transformed. In winter, this species hibernate under logs, bark, or fallen leaves (Harding, 2000). Semlitsch and Bodie (2003) list the terrestrial migration distances from aquatic sites for amphibians and reptiles, including some species found in the study area, where distances range up to 1115 m. The targets for the maintenance of flora and fauna biodiversity are for the most part reflected in those cited for the habitat types listed above. Linkages are an important consideration for the maintenance of sustainable populations and are therefore discussed separately below under Objective 3.3. Targets See targets listed for wetlands, woodlands, and other vegetation community types; Provide for linkages; and Provide buffers. (tremaine_dundas subwatershed study september_2009.doc)

22 Goal #3, Objective 3.3 To ensure that existing wildlife linkages are preserved and that opportunities for improving these linkages are considered/implemented as part of any future development. As discussed earlier, a range of linkage types and opportunities currently exist within the study area. However, consideration for retaining wide, contiguous forested connections is necessary. In light of the objectives of maintaining sustainable woodlands, wetlands, watercourse corridors and wildlife populations, linkages are an important part of the Subwatershed Study management strategy. Linear habitats either associated with riparian habitats or other upland features may provide an intrinsic habitat function (Riley and Mohr, 1994). Ecological linkages must be designed with an understanding of the species that will use the connection. Within the study area, Bronte Creek provides a broad wooded linkage to lands north of Highway 407 and south of Dundas Street. This is a key ecological corridor that should be focused on for the identification and/or creation of forested linkages. A diversity of linkage types and a measure of redundancy in the linkage network should be considered to provide a range of movement opportunities. Linkages should also been set aside and maintained to provide recreational opportunities, such as biking and hiking trails. Targets Maintain ecological linkages associated with tributaries of Fourteen Mile Creek. Maintain ecological linkages between upland woodlands and the adjacent natural areas of the Bronte Creek valley. Where a road crossing is unavoidable potential impacts to wildlife movement should be considered and minimized by implementing mitigation measures such as, minimizing the length of the crossing, utilizing special road design (width, boulevard, traffic calming, signage, wildlife crossings, etc.) to enhance wildlife movement opportunities and reduce the threat to wildlife movement; and Maintain the regional ecological linkages within and beyond the TDSPSA provided by natural areas along the Bronte Creek valley Goal #3, Objective 3.4 To ensure that development in the stream corridor is consistent with the historical and cultural character of the surroundings and reflects the need to protect visual amenities. The historical and cultural characteristics of the catchments have been considered primarily through the Secondary Planning Process but also in the subwatershed analysis and management strategy. Besides providing an environmental resource through vegetation and wildlife habitat, the terrestrial features, including stream corridors, provide a cultural and visual feature. (tremaine_dundas subwatershed study september_2009.doc)

23 Targets Presence of visual and historic amenities through the subwatershed and Secondary Planning Processes Goal #3, Objective 3.5 To ensure that the recreational and fisheries potential of a watercourse are developed to the fullest extent practicable. The assessment of the Bronte Creek corridor and the development of a management strategy has included the protection of existing conditions and the potential for enhancement. In this way, the fisheries potential will be developed to the fullest extent practicable. Recreational potential will be provided through trails and park planning developed in conjunction with this and the Secondary Planning Process. Information on the management related to fisheries is presented under Objectives 1.3 and 2.3. Targets See discussion under Objectives 3.1 and Management Strategy Overview The management strategy has been developed to meet the goals, objectives, and related targets outlined in Section 5.2. The proposed management strategy addresses both the form and the function (or process) that support those characteristics. The characterization and analysis provide an understanding of the environmental conditions and related processes (as well as potential impacts) throughout Burlington East. Based on this understanding of form and function in the area, an ecosystem approach was used to develop a strategy that will protect and enhance the watershed features Overall Approach to a Management Strategy To adhere to the overall approach that protects and enhances the natural environment in a sustainable fashion, the management strategy must be comprehensive and address all of the key components and processes. These components include: NHS The NHS approach is a land use planning tool intended to mitigate the impacts and stresses associated with urban development. It involves establishing a system of protected areas that consists of large core areas connected by functional ecological linkages. The NHS consisting of a system of connected core areas protects significant features and functions per the 2005 PPS, (tremaine_dundas subwatershed study september_2009.doc)

24 preserves and enhances biodiversity, and accommodates the natural movement of plants and animals that is necessary for their-long term viability; Terrestrial and Wetland The development of a management approach for terrestrial and wetland features that will protect and enhance overall biodiversity including the flora and fauna associated with terrestrial and wetland features in an environmentally sustainable fashion. This includes the provision of a corridor system to provide for any necessary linkages for wildlife and plant movement; Streams The provision of a corridor system for streams that have been identified as having environmental characteristics or watershed functions that require protection and/or enhancement to meet the watershed goals and objectives. A riparian corridor approach is to be applied which will consider all of the stream functions including: - Hydrologic; - Hydrogeologic; - Geomorphologic; - Environmental; - Compatibility with Adjacent Lands Consideration needs to be given to the compatibility of land use adjacent to the NHS can occur with certain land uses; and SWM The development of an approach that will protect and enhance environmental characteristics through managing related stormwater response and conveyance processes Management Implications in the TDSPSA The text in the preceding section provides a generic description of management strategies that is applicable to most subwatershed studies. The challenge inherent in this Subwatershed Study is taking the general principles of a management strategy and applying them to a relatively diverse landscape and environmental conditions. For instance, the TDSPSA encompasses an assemblage of numerous catchments that sustain a varied natural heritage. These challenges can, however, be overcome through the application of sound, comprehensive assessment and science. Before presenting the overall management strategy, a review and discussion regarding several of the physical issues and variability across the study area which influence the management strategy is warranted Headwater Areas Drainage Density Targets Based on the analyses presented in Section 4.7, regional drainage density targets were met on a subcatchment basis within the TDSPSA through the identified maintenance of open channels Natural Heritage System Terrestrial and Wetland Wetlands Wetlands are very sensitive to impacts that result in changes to the quality or quantity of water that enters and sustains the wetland. Wetlands are also sensitive to human use, particularly trampling of vegetation and compaction of soil which may also result in hydrologic impacts as water is channelled along footpaths. SWM best practices should be applied and stormwater inputs to the NHS should attempt to emulate to the greatest degree possible predevelopment conditions related to water quality and water (tremaine_dundas subwatershed study september_2009.doc)

25 quantity inputs, seasonal periodicity of water inputs following rainfall events and the geographic location of water inputs from across the landscape. Human use should be directed as far away from wetland limits as possible. If trail development is warranted to cross wetland areas or for natural heritage appreciation, trails must be located with the assistance from, and approval of, Conservation Halton and appropriate boardwalk design used to prevent impacts to vegetation or water movement. Buffer areas for wetlands should be permitted to regenerate naturally and where necessary trails may be located in buffer areas Woodlands The woodlands in southern Ontario have been fragmented by human land uses (e.g., agriculture, roads, aggregate extraction, and urbanization) and often consist of relatively small patches with little in the way of interior woodland conditions due to impacts that are known to occur within 100 m (or more) from the edge of woodland patches. Even the seemingly large contiguous woodland along Bronte Creek and the adjacent tableland within the TDSPSA have relatively little interior due to their linear shape. Protecting and providing opportunities for enhancement of these forest areas is important to protecting high quality woodland habitat that supports area demanding species. All woodland areas are included within the NHS and buffers are proposed to protect woodland edges from adjacent land uses. Currently some water enters woodlands as diffuse overland flow from adjacent agricultural lands that may be developed. The post development management of stormwater should maintain to the extent possible diffuse overland water flow to woodlands. Substantial impacts to woodlands were noted during field observations, including: Proliferation of trails that eliminate vegetation and where present on steep slopes lead to increased soil erosion; Exotic plants, particularly garlic mustard, dominate understory vegetation within some woodlands; Overgrown savannah was noted by the presence of open grown trees and remnant prairie vegetation suggesting more open communities were once present and these areas may have included a greater diversity of native savannah species; and In some areas woodlands have been used to dump refuse from past agricultural land users. In consultation with relevant stakeholders (e.g., Conservation Halton, City of Burlington, Halton Region, landowners, naturalists groups, and trail users) there is a need to undertake a study that will develop a comprehensive trail management plan for the TDSPSA, particularly for the Bronte Creek valley but also for adjacent tableland woodlands and proposed development areas. Trail management will need to consider how trail users are using adjoining areas located to the north and south along Bronte Creek. Based on the proliferation of trails observed during field work completed for this study, there is an urgent need for the closure and restoration of some trails, and the maintenance and signage of designated trails. Controlling exotic plants is a difficult and labour intensive (costly) undertaking, however, remnant understory vegetation was observed even within areas dominated by exotic plants such as garlic mustard. There is an opportunity therefore, to utilize proven control measures to reduce exotic plants and thereby provide opportunity for the re-establishment of native plants. Development of an exotic plant (tremaine_dundas subwatershed study september_2009.doc)

26 management plan is necessary to provide direction and methods for implementation of effective restoration. Methods used to restore and manage savannah remnants in Bronte Creek Park, located to the south, may be examined to determine their applicability to restore and manage similar vegetation located within the TDSPSA Other Vegetation Communities A relatively large area of open habitat (Cultural Meadow (CUM)) is included within the TDSPSA NHS immediately south of Hwy 407. Open habitats, in particular open grasslands, contribute to biological diversity and are a desirable component of the NHS. There are a number of species of birds and insects that require open habitats and as ongoing development reduces areas of open habitat, these species are declining in numbers in southern Ontario. The large area of open habitat within the TDSPSA NHS offers an ideal opportunity to promote and maintain open grassland/meadow areas for such species. Maintaining open habitat will require that woody species which invade open areas through natural succession be periodically removed using a brush-hog, chain saw or other appropriate means. The time interval for this maintenance will depend on the rate of woody species invasion. Maintenance may be expected to be every two to five to ten years. Some well-established meadows, particularly those that establish on former pasture lands, show significant resistance to succession and can persist in excess of ten years without maintenance. Maintenance should be done outside of the breeding bird season to prevent destruction of nests; preferably in the autumn. The agency responsible for the maintenance of open habitat has not been identified at this time, but may include the Province, Halton Region, City of Burlington, or Conservation Halton Significant Hedgerow Five hedgerows, H4, H5, H6, H7, and H8, (see Figure 3.3.1) are identified as significant hedgerows based on the dominant mature, healthy native hardwood tree species present. In addition to the valued tree species and the wildlife habitat they provide, these hedgerows also perform important ecological linkage functions. Hedgerows H4 and H5 are wholly protected within the NHS. To the greatest extent possible trees within hedgerows H6, H7 and H8 should be protected. This may involve appropriate configuration of lots, placing hedgerow trees within areas along lot lines and minimizing grade changes to facilitate tree saving. Where roads are proposed to cross significant hedgerows road location may be adjusted to preserve trees to the greatest extent possible and alternative road standards may be considered to protect trees. Following these recommendations as more detailed land use plans are developed for the TDSPSA, significant hedgerows should be protected to the greatest extent possible to preserve their ecological features and functions. Healthy native trees present within other hedgerows should also be considered for protection within any proposed development. (tremaine_dundas subwatershed study september_2009.doc)

27 Linkages Maintaining functional ecological connections for short and long-term wildlife movement patterns is a founding principle of the NHS. Areas intended to enhance and protect ecological linkage functions from changes in land use form part of the NHS. These include a 200 m wide ecological linkage between the large square forest (FOD5-2) and the adjacent pond and wetland, and a 100 m wide ecological linkage between the area of cultural woodland (Cultural Woodland (CUW) 1a) and the Bronte Creek valley. These linkages are intended to support daily, seasonal and long-term movement of all organisms, including plants and animals. For plants movement occurs through a variety of dissemination mechanisms such as wind and animals including insects, birds and large and small mammals. For larger animals and birds, movement through ecological linkage corridors may be relatively safe and easy. For smaller animals, insects and molluscs, movement may rely on the presence of suitable (high quality) contiguous habitat that permits movement among overlapping populations, a process that may take several generations. Management of ecological linkage areas for the TDSPSA is based on providing high quality woodland habitat similar to the areas that are being connected. The preferred management approach is to prohibit the development of roads through natural heritage features or across linkage corridors. Should it be necessary to construct a road, an assessment of the following factors should be undertaken to design appropriate mitigation measures to achieve the best possible conditions for ongoing wildlife movement: Road conditions such as width of roadway, traffic volume, traffic speed, road grade, road side slopes, road barriers, and road lighting; Known movement patterns of wildlife daily and seasonally and species most likely to cross; Topography in the vicinity of the road crossing that may facilitate movement beneath the roadway via a constructed wildlife underpass, culvert or span bridge; Opportunities for traffic calming through road modifications such as reduced traffic speed, road narrowing at NHS crossing, signage, road lighting, and improved sightlines; Temporary road closure if there are well known short-term movement patterns (e.g., amphibian crossings from upland to wetland for breeding); Provision of alternate basking sites away from roads crossings for cold blooded reptiles if required; Provision of appropriate nesting habitat for reptiles and amphibians away from road crossings if required; and Wildlife crossing structures that include the design and construction of funnelling structures to lead animals into crossing structures Preferred Management Approach to Terrestrial Features Management of the terrestrial and wetland resources is based on the identification of a NHS that protects the most significant natural heritage features and protects intervening habitat that performs ecological linkage functions critical to the daily, seasonal and long-term movement requirements of resident wildlife. The NHS is a comprehensive approach intended to provide long term protection significant wildlife habitat present within the TDSPSA. In addition, it is recognized that change from the current agricultural land use to more intensive urban land uses will result in impacts to adjacent natural areas protected within the (tremaine_dundas subwatershed study september_2009.doc)

28 NHS. Further protection of natural heritage features is therefore provided by buffers that are incorporated in to the NHS as proposed below. All areas of the NHS are sensitive to human use impacts. Vegetation trampling, soil compaction/denudation, introduction of exotic species, free-roaming pets and dumping are some of the impacts that can occur without carefully considered access, trails, signage and education for public use of natural areas. Currently unrestricted use of the Bronte Creek valley has lead to a proliferation of trails and substantial damage to understory vegetation and soils. In addition, many natural habitats have been severely impacted by non-native plants, particularly garlic mustard. There will be a need therefore to carefully manage public use of the NHS and to initiate restoration of areas currently degraded. The terrestrial and wetland constraint areas identified for the TDSPSA consist of the Bronte Creek valley, significant woodlands, wetland areas, linkage areas, and significant hedgerows. Collectively these areas form a linked NHS which protects the most significant natural areas present and provides functional ecological linkage corridors required to meet the daily, seasonal and long-term movement requirements of the resident species. The Greenbelt NHS is included and forms a substantial portion of the NHS proposed for the TDSPSA. The Greenbelt NHS includes the Bronte Creek valley, the associated valley slope and contiguous tableland woodlands, the pond and associated wetlands, and a large area of cultural meadow located in the northern portion of the TDSPSA on either side of the rail line adjacent to the Bronte Creek valley. The large area of cultural meadow will provide an area open habitat of for wildlife, this is particularly important given the number of open habitat species recorded and the loss of open habitat that will occur as the open agricultural fields undergo development. Some development concepts may include the need for the construction of roads within the NHS; while the preference is to have no roads within the NHS the primary concerns to be considered in the management approach are to avoid natural heritage features such as woodlands, wetlands and significant species (in particular butternut) and to minimize and appropriately mitigate impacts to natural heritage functions such as ecological linkage and hydrology. To provide long-term protection of the TDSPSA NHS from changing adjacent land uses the following buffers are recommended for the NHS: 30 m buffer for Key Natural Heritage Features located within the Greenbelt NHS that occur along the boundary of the Greenbelt NHS within the TDSPSA; 0 m buffer for the Greenbelt NHS where there are no Key Natural Heritage Features present; 30 m buffer for wetlands greater than or equal to 2 ha in size located outside the Greenbelt NHS; 15 m buffer for wetlands less two ha in size located outside the Greenbelt NHS; 30 m buffer for significant woodlands located outside but contiguous with the Greenbelt NHS; and 0 m buffer for hedgerows. (tremaine_dundas subwatershed study september_2009.doc)

29 5.3.4 Natural Heritage System Streams An overall evaluation and development of a classification of the riparian corridor by reach was carried out. This evaluation has led to the development of three categories of stream for management high, medium and low constraint streams (see Section 4.0). The following sections summarize the basis upon which riparian corridor classifications were established on an individual discipline basis Geomorphology The role of the stream corridors is multipurpose from a geomorphic standpoint. It not only provides flow and sediment storage during high flow events, it also acts as a filter to prevent sediment and particulate inputs from surface runoff from embedding coarse substrates within the streams. The maintenance of riparian vegetation within the stream corridor acts to stabilize banks and also provides inputs of organic materials and debris which aid in creating a diverse morphology. The meander belt width incorporated into the corridor allows the channel to migrate naturally within its floodplain without the loss of property or structural integrity. Streams Corridors Conveyance Corridors 1. High Geomorphic Classification: One management option - These conveyance corridors are no touch reaches that have been identified as sensitive to changes in the flow regime and/or have a well-defined morphology and must remain undisturbed within the corridor boundaries. 2. Medium Geomorphic Classification: These reaches may or may not have a well-defined morphology but do maintain geomorphic function and have potential for rehabilitation. Management options for these reaches include the following: a. Do Nothing: Leave the corridors in their present condition and develop outside of their boundaries. b. Enhance Existing Conditions: Maintain the present location of the corridor but enhance the existing conditions (e.g., bank stabilization, re-establish a meandering planform, and/or connect channel to functioning floodplain). c. Re-locate and Enhance Existing Conditions: Many of the reaches within the study area have undergone extensive straightening and modification for agricultural drainage purposes. As such they are not as sensitive to relocation and would benefit from enhancements such as the reestablishment of a meandering planform with functioning floodplain and development of a rifflepool morphology. 3. Low Geomorphic Classification: In general, these reaches consist of ephemeral headwater systems that display poorly defined bed and banks but do perform a geomorphic function through the conveyance of flow and sediment. Management options for these reaches include the following: a. Do Nothing: Leave the corridors intact and develop the surrounding lands. b. Combination of SWM and Open Conveyance Techniques: The function of headwater streams can be mimicked through the implementation of SWM techniques with sufficient open conveyance systems such as backyard swales. (tremaine_dundas subwatershed study september_2009.doc)

30 c. Open Conveyance Techniques: The function of the ephemeral swales is replicated entirely through a system of open conveyance techniques (e.g., backyard swales) Fisheries Streams must be provided with a riparian buffer to protect them from the impacts of urban development and associated human activity. According to a review article by Castelle et al. (1994), buffer widths in the 15 to 30 m range are required to maintain the biological components of many wetlands and streams. Castelle et al. (1994) also indicate that the need for larger buffers increases in some situations, for example, where a wetland or stream is highly valuable or the adjacent land use is intense. Environment Canada (2004) recommends a minimum buffer of 30 m for streams and recognizes that vegetating the riparian areas associated with lower order streams is very important. The Greenbelt Plan (MMAH, 2005b) outlines policies for Key Natural Heritage Features within the Protected Countryside. In the case of wetlands, seepage areas and springs, fish habitat, permanent and intermittent streams, lakes, and significant woodlands, the minimum vegetation protection zone shall be a minimum of 30 m wide measured from the outside boundary of the Key Natural Heritage Feature or Key Hydrologic Feature. MNR (1994) Fish Habitat Protection Guidelines for Developing Areas recommended buffers of 15 m from important fisheries habitats. This latter dimension is in common use by Conservation Authorities in southern Ontario. For watercourses which support redside dace, the buffer requirements of the DRAFT Recovery Strategy for Redside Dace in Ontario (Dextrase et al., 2005) are recommended. This would result in buffer widths of 30 m for survival habitats. The definition of survival habitat in the recovery strategy is as follows: Survival Habitat is considered to be all reaches currently occupied by redside dace. Survival habitat consists of two elements. The first element includes bankfull stream width and the meander belt width of the stream. The second element of survival habitat includes associated riparian habitat that is a minimum of 30 m from the meander belt (measured horizontally). For the purposes of this Subwatershed Study, no reaches within the study area support redside dace and therefore would not be considered as survival habitat requiring this 30 m setback. However, Bronte Creek, the pond, and its outlet channel are situated within the designated Greenbelt and therefore would be subject to a minimum vegetated protection zone of 30 m. For non redside dace streams, outside of the Greenbelt a minimum buffer width is recommended that would provide some level of protection for the stream. Review of the literature and of current practice in southern Ontario suggests that a minimum width of 15 m would be appropriate and this width is recommended. There is support in the literature for the use of fluvial driven stream corridors to protect aquatic habitat (Brosofske et al., 1997; Naiman and Decamps, 1997; Naiman et al., 1993; Gregory et al., 1991). Because the habitat value and vegetation composition of a riparian zone is largely driven by floodplain and fluvial processes, it is sensible to use the stream corridor widths developed for this study as a result of floodplain and fluvial characteristics as a minimum measure to protect fish communities and aquatic habitat within the watercourses. The buffers created by the fluvial and floodplain management strategies (tremaine_dundas subwatershed study september_2009.doc)

31 developed for this Subwatershed Study are generally sufficient to achieve the target buffer width for survival habitat of 30 m described in the DRAFT Recovery Strategy for Redside Dace in Ontario (Dextrase et al., 2005) and certainly achieve the recommended minimum width of 15 m (see above) for all aquatic habitat. In some cases, these fluvial/floodplain buffers far exceed these recommended buffer widths. Wherever the recommended buffer widths are not met by floodplain and fluvial corridors requirements, it will be necessary to include upland habitat outside this zone to maintain the recommended buffer width along all watercourses. Limiting the use of these riparian buffers for trails and other urban intrusions increases their effectiveness in terms of the functions described above. However, the desire to achieve aquatic habitat benefits must be balanced with the need for recreational opportunities within the urban environment. For example, if intrusion into stream buffers on sensitive streams can be limited in return for placement of trail features within the buffers of less sensitive streams, this is desirable. As outlined in Section 4.9, categorization of environmental habitats allows for the identification of the relative importance of the habitat, and the resulting relative sensitivity to development. Analysis of the various components of the categorization system leads to an overall rating of critical, important or marginal for each stream reach (Table 4.9.2). An additional category of no habitat was also included to identify those reaches which contribute flow to downstream reaches but show no evidence of any in-situ aquatic habitat. As a result of this assessment, only one watercourse within the study area (Bronte Creek) was categorized as critical habitat (Figure 4.9.1; Table 4.9.3). The northwest tributary to the west branch of Fourteen Mile Creek was categorized as important habitat, while the southeast tributary to the west branch of Fourteen Mile Creek was categorized as no habitat. Both the pond and it s outlet channel were classified as providing marginal habitat. Management Recommendations Broad Level Management Recommendations have been discussed above to achieve certain targets on a system wide basis. The list below outlines general management practices which, if implemented, should aid in achieving broad level targets related to enhancing riparian canopy and moderating stream temperatures. These recommendations fall into the following broad categories. Any watercourse may have one of these recommendations associated with it or, in some cases, a combination of more than one recommendation. Plant woody vegetation to supplement existing herbaceous vegetation where an herbaceous cover is well established. Allow vegetative succession of woody vegetation to continue undisturbed. In these cases woody vegetation is far enough advanced that natural succession should be left alone. Encourage herbaceous vegetation and discourage woody vegetation within the first 2 to 3 m from top of bank for redside dace survival habitat. Bank revetment required to repair bank erosion problems. Very site specific areas where advanced erosion is evident. Relocation of channel recommended to mitigate negative land use practices. For example, relocating a channel out of a roadside ditch. If the existing vegetation community is doing well, it should not be (tremaine_dundas subwatershed study september_2009.doc)

32 disturbed. This applies mainly to heavily wooded reaches or reaches where shrubs and herbaceous vegetation is very well established. Do not modify channel form if SAR are supported in the reach. Riparian plantings and vegetation enhancement can occur but the channel is stable and should not be modified in any way. No management required if reaches have been designated as supporting no in-situ aquatic habitat. Stream Corridors Many of the aspects of the management of linkages are discussed in Section In some cases, the existing riparian vegetation found within stream corridors is limited or not existent. Therefore, the issue of protecting the riparian vegetation is not as important as encouraging the establishment of vegetation in these areas. The stream corridors are a composite of a number of factors that result in many cases in widths of 50 m (+/-). The preferred management of the corridors from a linkage perspective would be to retain existing woody and wetland vegetation associated with the corridors, and allow for the establishment of woody vegetation within the stream corridors. This is consistent with the management recommendations from an aquatic perspective (see above). The maintenance of existing vegetation associated with the stream corridors is related to the flow within the channels or in the case of wetlands, the factors that drive the water regime within them. See Section for a discussion of the issues associated with the lands through which the stream corridor linkage traverses Hydrologic Function Flood Protection As part of the stream corridor management strategy, the stream corridors that require protection and the associated level of protection is illustrated in Figure Figure shows stream reaches that have been classified as being either those that require form and function to be maintained (red), those that are required to remain as open watercourses but whose form can be altered (blue), or those whose geomorphic function can be duplicated through the use of backyard swales or SWM ponds (green). In section streams were classified considering a range of form and function characteristics including hydrologic conditions; water quality, presence of a valley, hydraulic conveyance (including ability to store streamflows) and correction to headwater systems. The ability to detain/retain stormwater in as a floodplain function, is an important role of stream system. Similar to the initial detention/retention of water on a landscape, when streamflows are high enough to go into overbank areas, waters are temporarily stored, which tends to reduce peak flows. This function was included in the overall analysis in section in conjunction with the other functions of streams discussed in this section as well as As part of the management strategy the current hydrologic function of red and blue streams are to be retained. This will be accomplished by retaining the current corridor (or possibly re-creating in the case of (tremaine_dundas subwatershed study september_2009.doc)

33 Tremaine and Dundas Secondary Plan Subwatershed Study Highway W -1 7 Legend Reach Breaks Contour 14W-17 Reach Designation Riparian Corridor Classifications High Medium Low Bronte Creek Wetland TR 1 Tremaine Rd BC-R2 BC Meters W14 C 17 b Dundas St Datum: NAD 83, Zone 17 Source: Town of Oakville 1:6,000 September 2009 Figure G:\Prj22600\ Tremaine Subwatershed Study\GIS\Report Maps BC - a R1 C W Riparian Corridor Classification

34 a blue stream) including it s current stage-storage-discharge characteristics. Green streams will be maintained as open drainage swales, where possible, but can be piped if needed. The red streams do not have any management options that may be used to increase their protection from flood. For those streams that must remain as they exist today, development will not be permitted within the floodlines that are regulated by Conservation Halton. For the blue or green stream reaches, there may be some opportunities to deepen the streams, combine adjacent streams or reroute the streams to a more desirable location. Any of these options will change the preliminary floodlines, and perhaps allow for development in areas that may not currently allow development due to the presence of floodlines. In any event, each of these potential opportunities should be explored at the EIR (see Section 6.0) stage and be completed under the authority of Conservation Halton. It is important to note that any of the changes proposed to the cross-section of the blue streams must also maintain the storage requirements discussed in Section Hydrogeology Within the study area, there are specific geological, physiographic and hydrogeological features that have both created existing conditions and will contribute to the overall health of the watercourses in the future. These must be taken into account in developing an effective management strategy for the area. With respect to stream classification and management, consideration was given to the identification of recharge and discharge function related to contribution of baseflow to streams. This can include local recharge/discharge within corridors that occurs during high flow depths (water infiltrates into upper soil layers during high flows and discharges back to streams during low flows). Alternate recharge/discharge can occur when water infiltrates to the groundwater system which is intercepted by a stream system farther away in the form of seepage or spring discharge to the stream. The recharge /discharge characteristics were considered in section in classifying streams. Development of the study area uses an 'environment first' principle, which is a guiding principle for the development of the community. One component of achieving this objective is the integration of Best Management Practices for low impact development, to maintain as closely as practicable, predevelopment groundwater conditions after development. With the inevitable changes in impervious areas, and potential changes to ground water quality and quantity, Best Management Practices that promote groundwater infiltration/recharge post development for the purpose of trying to maintain post development infiltration to predevelopment levels makes a significant contribution to mitigating the effects of urbanization. Groundwater resource management in the urban setting has two main components. The first component involves managing infiltration in an urban environment. Considering the low permeability soils in the area and at the site, recharge enhancement potential is low. Although the use of infiltration techniques will replace some of the infiltration lost as a result of development, it is virtually impossible to match preconstruction infiltration and post construction infiltration. (tremaine_dundas subwatershed study september_2009.doc)

35 The second component is management of groundwater discharges. Since there is virtually no groundwater discharge to surface water courses, other than a component of regional discharge to Bronte Creek, the need to manage groundwater discharge is low. Infiltration Management of the groundwater resources in the study area for the future focuses on management of the hydrologic cycle. Given that urbanization will change components of the cycle, including a decrease in infiltration, the overall goal will be to maintain infiltration as close to current levels as possible. Within areas that will be preserved, the hydrologic function will remain the same. This includes the amount of recharge entering the system. In areas where development will occur, the increase in impervious areas will decrease infiltration and measures are needed that will help offset the predicted infiltration decrease. To mitigate the effects of urbanization, in particular reduced infiltration, the following potential measures (above and beyond traditional lot level controls) were considered: Rain water harvested from building rooftops could be used for irrigation (underneath buildings): - Would require construction of water storage and distribution facilities at the site. Also involves use of some form of irrigation system; Infiltration systems: - Low permeability soils and the relatively shallow depth to water table precludes the development and successful implementation of large scale infiltration facilities; and Green roofs and porous pavement: - For climates with a significant freeze thaw cycle the use of permeable pavements may result in significant maintenance. In addition the technology for green roofs is in its infancy. This technology should only be considered on a case by case basis. The use of roof drainage as irrigation water or for discharge to unpaved areas for natural infiltration is an effective means of helping to balance the pre to post construction infiltration for the long-term. These facilities should be designed with an overflow back to the SWM pond to avoid backflow and ground surface flooding. Other infiltration mitigation measures could be considered, although the low permeability of the surficial soils constrains the amount of additional infiltration that can be added to the subsurface. Infiltration systems must consider the hydraulic conductivity of local soils, topography, and vegetative cover. Using an average hydraulic conductivity for the Halton Till of 1.2 x10-7 m/sec, which considers the fractured nature of the clayey silt till, about 86,200 m 3 /yr can be infiltrated post development. Groundwater Discharge The discharge component is present and does contribute to the overall health of Bronte Creek. Therefore, consideration must be given to the management of groundwater discharge areas in the Bronte Creek Valley. For groundwater discharge management the focus is the protection of groundwater discharge areas. The preservation of the riparian corridors is the most effective means of maintaining the identified (tremaine_dundas subwatershed study september_2009.doc)

36 groundwater discharges to the surface water system. associated recharge zones. Along with these discharge areas are their Considering the limited extent of the zones of influence that these small discharges have, the recharge that they receive is interpreted to occur close by. The riparian corridors likely capture much of the recharge area for these discharge zones. The protection and incorporation of groundwater related functions that play a role in the hydrologic response of a watershed role can be used as a management tool to assist in mitigating peak flow increases and erosion increase related to land use changes (i.e., urbanization and agricultural uses). These features primarily include wetlands, woodlands, and the storage contained in riparian corridors along a stream system Riparian Corridor Management In managing the stream systems (Red and Blue) they are to be protected, developed, enhanced and managed as fully functioning riparian corridors. A sufficient belt width is to be provided for to allow the stream to function in dynamic equilibrium, the overall corridor width is to respect hazard limits (flooding, erosion, slope stability) including setbacks, the vegetation and stream structure is to provide for terrestrial and aquatic function; the stage-storage characteristics are to be maintained for hydrologic functions and any hydrogeologic recharge-discharge function is to be maintained. Tributary 14W-17 of Fourteen Mile Creek crosses the northern corner of the study area, this tributary has been identified as a medium constraint (blue) stream and as such its features and functions must be maintained in their present location. The riparian vegetation associated with the tributary is a meadow marsh wetland (MAM2-2), dominated by reed canary grass. The wetland vegetation performs a filtering function that enhances water quality and provides shading to assist in maintaining the coolwater temperatures that characterize this stream segment. A 30 m setback is required along this stream and a 15 m setback is required by Conservation Halton (Ontario Regulation 162/06) for the wetland vegetation associated with this riparian corridor to protect and enhance the features and functions of the riparian vegetation from adjacent land use change. Conservation Halton policy does not permit the re-alignment of creeks such as 14W-17 that are located within Regulated wetlands. The development concepts reviewed in the Subwatershed Study do not propose relocation of this medium constraint (blue) stream. Should future development proposals propose relocation of stream 14W-17 this would require approval by Conservation Halton Considerations for Stream Relocation Some recognition of the importance of the existing stream geometry and morphology must be incorporated in the management strategy as modifications to these factors can negatively affect aquatic habitat and overall ecosystem health. Two management options were considered: A very conservative approach in which all streams remain where they are and no modification or relocation is considered; and (tremaine_dundas subwatershed study september_2009.doc)

37 An approach that considers the relative quality of aquatic habitats and the sensitivity of different habitats to modification and/or relocation. The results of this study show that there are distinct differences in the quality of aquatic habitats throughout the site. High quality aquatic habitats and important fish communities are supported by relatively undisturbed corridors with good riparian cover. It is essential that these features remain undisturbed to maintain the quality of the aquatic ecosystem. Therefore, it is recommended that any watercourse reach designated as critical or important habitat (see Section 4.9.1) remain in place and not be considered for relocation. Marginal habitats may be relocated provided that enhancement opportunities are considered in the design to reverse degradation and achieve a net gain in fish habitat. It will also be important to demonstrate no net loss of aquatic habitat productivity as a result of the relocation as this is a requirement of Section 35(2) of the Federal Fisheries Act and an authorization from the DFO will be required for the relocations. If it is deemed necessary to relocate a watercourse, it is important that fluvial and geomorphic functions are maintained. At a minimum, the stream must continue to deliver the same quantity and quality of water to downstream reaches. Opportunities to enhance form should be considered to improve quantity and quality if possible Compatible Land Uses Adjacent and Within the Natural Heritage System Compatible Land Uses Adjacent the Natural Heritage System Generally, the issue of compatible land uses is addressed in planning and development studies through identification of a suitable buffers in conjunction with structural setbacks from selected features. When smaller buffers are used, compatible land uses become more of an issue. In conjunction with the NHS approach, suitable buffers have been recommended and are intended to be included within the NHS to protect NHS features from urban land uses that may be proposed adjacent to these natural areas Compatible Land Uses Within the Natural Heritage System SWM Facilities SWM facilities have received considerable research into the suitability of locating these features adjacent to, and within, natural areas that may form a NHS. The features within the TDSPSA do not present suitable areas to accommodate the inclusion of SWM facilities, as such SWM facilities are not considered a compatible land use within the NHS. (tremaine_dundas subwatershed study september_2009.doc)

38 Road Crossings It is recognized that development may result in construction of one or two road crossing of the NHS within areas that provide ecological linkage between tableland woodlands and adjacent natural areas associated with the Bronte Valley. Should road crossings be approved, consultation with Conservation Halton, Municipalities and the MNR should be undertaken to discuss appropriate road design standards and acceptable ecological linkage mitigations measures. Section provides a discussion of design considerations for road crossings. These measures may include, but are not limited to: Use of plantings and wing walls to direct wildlife using the linkage to culvert/bridge crossings; Use of ecopassages as a mitigation measure should a road crossing be required; Design of all culverts/bridges to accommodate wildlife movement; Consideration of alternative road designs to minimize the width of the roadway; Locating services under the roadway is recommended to minimize roadway right-of-way; and Road alignments that avoid woodland and wetland features. Trails Recreational trails for pedestrian and bicycle use may be permitted within the NHS. The location and design of trails will require special consideration and evaluation when to avoid impacts to the NHS. A comprehensive master trail plan for the NHS will be the best strategy to rehabilitate existing degraded areas, to discourage new informal trail creation and to provide low impact and safe access for the public wishing to use the NHS. The preparation of a Trail Management Plan should be undertaken as part of the completion of the Secondary Plan. The following should be considered when planning the location of trails: Trails within the NHS should use existing trails and be co-located with any proposed road crossing; Trails should be located along the edge of woodlands to protect interior conditions where present; Trail systems should be located within NHS buffers wherever possible; Existing areas where there is a proliferation of trails will require trail closures and trail rehabilitation; and Should trails be situated within the regulated limits of wetlands approval from Conservation Halton is required. The MNR and Conservation Halton will need to be consulted as part of the evaluation of the placement and design of trails within the NHS Grading and the Natural Heritage System In most cases it is recommended that any grading required for development on lands outside the NHS match existing grades at the outer boundary of the NHS. That is, grade changes, such as cutting or filling, are strongly discouraged within the NHS and are only permitted following the recommendations outlined below. The extent of grading would be detailed as part of the EIR studies. (tremaine_dundas subwatershed study september_2009.doc)

39 In some cases re-grading required for development outside of, but adjacent to, the NHS may extend into the NHS buffer areas. In these cases the following recommendations are provided: Grading must not negatively impact existing natural features within the NHS, drainage or hydrogeological functions; Grading can only extend into agricultural lands that form the buffer around the perimeter of the NHS; Matching slopes within the NHS should not to exceed a gradient of 3:1; Grading within buffers is not permitted within 10 m of wetlands or 1 m of the dripline of woodlands; and Grading is only permitted to match grades that may be required outside the NHS. In addition, a maximum of half the slope length required to match grades can occur within the NHS (i.e., the fill slope would be shared between the NHS and the neighbouring development area). Proposed grading for development will be subject to an EIS to demonstrate that there will be no negative impacts on the NHS as a result of the proposed grading, and sediment and erosion control plan. The grading shall not impact existing NHS due to erosive flows and consideration should include cross slope drainage and spreader swales. The exact controls that may be needed will be determined at the design stage in consultation with the Conservation Authority. As a part of re-grading topsoil stripping will be required and is permitted based on limits outlined above. Newly graded slopes will be topsoiled, planted, and stabilized immediately after construction Stormwater Management Hydrology Peak Flow and Erosion Control The protection and incorporation of features that play a role in the hydrologic response function of a watershed is a management tool that will assist in mitigating peak flow increases and erosion increase related to land use changes (i.e., urbanization and agricultural uses). These features primarily include wetlands, woodlands and the storage contained in riparian corridors along a stream system. In the case of the TDSPSA, the hydrologic role of the terrestrial features (woodlands and wetlands) and stream riparian corridors have been taken into consideration in the characterization and analysis. The hydrologic role of the larger features can be preserved through their protection and management. The development of this approach is also discussed through the environmental objectives and geomorphologic objectives of the stream system. With the smaller features, protection of the hydrologic function of these features can be provided through either preserving all of these features or a combined approach of replacing their function through SWM and/or preserving selected features. Given the fact that many of the smaller features have been disturbed by current land use, the lack of practicality of preserving these features over the long-term and the variability in their environmental role, the best approach is judged to include selective preservation/rehabilitation of features and the use of SWM to duplicate the role of the features in their hydrologic response function. (tremaine_dundas subwatershed study september_2009.doc)

40 Management of the groundwater resources in the study area for the future focuses on management of the hydrologic cycle using LID technologies. These include enhancing infiltration to reduce the volume of runoff that must be managed. These are discussed in Sections and Given that urbanization will change components of the cycle, the overall goal will be to maintain infiltration as close to current levels as possible. Within areas that will be preserved, the hydrologic function will remain the same. This includes the amount of recharge entering the system. In areas where development will occur, the increase in impervious areas will decrease infiltration and measures are needed to create infiltration opportunities that will offset the predicted infiltration decrease. Taking this approach will reduce the impact to the groundwater system, including limiting changes in depths to groundwater, limiting changes to groundwater quality, and ensuring the continuity of discharge to local watercourses. Peak Flow Control Maintaining peak flow rates at existing levels will require infiltrating or detaining new development runoff. If stormwater detention facilities are utilized, then outflow rates from a development will be determined for each return period using unit area flow rates. Unit area peak flow rates are shown in Table for each return period and the Regional Storm. The unit area peak flow rates are based on GAWSER simulated peak flow rates. These were developed to provide targets for SWM quantity control that would be refined during the development application phase. Control to existing condition peak flows is required to mitigate increases in flood potential in the receiving watercourses. The unit area peak flow rates will be used to calculate peak flow rates for each development under existing land use conditions. Results from the detailed hydrologic analysis will be approved by the City of Burlington and Conservation Halton. The results will include revised unit area peak flow rates for the watershed. SWM techniques have the potential to mitigate issues associated with the change in land use (i.e., increased surface runoff). Open conveyance systems such as backyard swales increase flow detention and evapotranspiration, creating a less flashy hydrograph by decreasing peak flows. SWM ponds also act to attenuate and moderate flows within the stream network. Included in this would be an appropriate erosion threshold, that would be quantified for the most sensitive channel reach in the downstream area. Control to existing condition peak flows is required to mitigate increase in flood potential in the receiving watercourses. This is necessary to protect private and public property and to ensure there is no increased risk to life along the receiving watercourses. In the case of a significant valley system such as the Bronte Creek valley, where it consists primarily of public property, consideration can be given to not requiring control to existing condition level for the Regional Storm as long as the following criteria are met: There is no flood potential to private property or where it can be demonstrated that there will be no increased flood elevations or velocities on private property; and (tremaine_dundas subwatershed study september_2009.doc)

41 Any predicted increases in flood elevations or velocities on public property will not result in increased risk by adversely affecting infrastructure or land uses such, as but not limited to, road crossings, parks, storm sewer outlets or exposure to users (e.g., pedestrian access along a trail or a vehicle on a roadway). Table Unit Area Flow Rates - Stormwater Pond Design Location Culvert GAWSER Regional Drainage GAWSER No. Hyd. No. m 3 /s year m 3 /s year m 3 /s year m 3 /s year m 3 /s year m 3 /s year m 3 /s Area ha Basin No. Bronte Creek Tributary Dundas Street Dundas Street Tremaine Road Tremaine Road Tremaine Road Tremaine Road Tremaine Road Outlet BCT 1001 & BCT 1002 N/A BC 1005 FM-D1 ( FM-D1 ) FM-T3 ( FM-D2) FM-T2 ( FM-D2) FM-T1 ( FM-D2) FM-T5 ( FM-D4 ) FM-T4 ( FM-D4 ) a b c a b Note: Pond Discharge Rates = Unit Area Flow Rate * Development Area To Outlet. ( FM-D2) Appropriate Culvert from NOCCSS Erosion Thresholds As noted above, the proposed SWM strategy needs an erosion component in order to ensure that the receiving channels will not experienced higher than normal rates of erosion. To accomplish this, a threshold flow needs to be incorporated into the design of the SWM facility. The threshold flow target is derived through traditional field protocols at the most sensitive reach downstream of the proposed facility, typically within two stream reaches of the site. The sensitivity is defined based on Rapid Geomorphic Assessments. Once the most sensitive reach has been selected, detailed field data is collected at a sufficient resolution to determine erosion thresholds using a range of hydraulic analyses. Typically, a shear stress value is appropriate, although depending on the nature of the channel (controlling factors such as vegetation), another approach such as permissible velocity or stream power may be more appropriate. The result should be compared against local values provided within this Subwatershed Study (see Table 4.7.1). Once the erosion threshold has been provided, exceedance analyses should be completed using a continuous flow model. Specifically, the frequency and duration of time (expressed as hours) that the erosive threshold flow is exceeded, in the predevelopment condition, is to be matched in the post development condition. It is acknowledged that matching may be difficult due to scalar factors, sensitivity of the analytical methods and degree of stability of the receiving channel. Generally, results (tremaine_dundas subwatershed study september_2009.doc)

42 that are within approximately 5% of the predevelopment condition are considered a match. Before this is accepted, work needs to be completed as to the likely effects and implications of this nominal increase to determine whether further mitigation or model refinement or monitoring is warranted. In this approach, any increase in runoff volume would be released from the SWM facility below the erosive threshold flow Water Quality The water quality control approach for SWM is recommended to focus on phosphorus, suspended solids, chloride, and temperature. These are intended to provide controls to meet the objective of not permitting further enrichment of the streams (i.e., nutrient control), fisheries protection and overall water quality protection. Fourteen Mile Creek will be managed to protect redside dace populations. Turbidity and sedimentation associated with agricultural activity and urban developments has been cited as a limiting factor for redside dace populations (Parker et al., 1988; Mckee et al., 1982; Becker, 1983). It is recommended that SWM facilities discharging to these watercourses be designed for an enhanced level of protection as per the MOE guidelines. Enhanced level of control for lands discharging to Bronte Creek have also been adopted. In addition, the goal of allowing no increases in phosphorus loads to Lake Ontario from new developments can be met by an enhanced level of control at the end-of-pipe, or combinations of controls. Section indicates the step-by-step procedure required to indicate how this goal is met. The other consideration with respect to SWM is the control of temperature with respect to the thermal regime of the creek. Measures that encourage infiltration of flow either at source, conveyance system or the outlet will help to alleviate temperature impacts. Temperature control at outlets can be provided through reverse-pipe outlets to ponds, rock filled cooling trenches and, measures combined with shading. Additional measures are available such as bottom draw outlets, shading, infiltration facilities and LID for temperature, and should be considered as part of the temperature control approach. Control of the amount of salt being discharged from SWM facilities is also very important. Environment Canada has released a notice with respect to the Code of Practice for the Environmental Management of Road Salts (Environment Canada, 2004). Presently, there is no technology for removal of salts in stormwater treatment. Annex A of the Environment Canada notice indicates that concentrations of chloride of approximately 140 mg/l should be protective of freshwater organisms for short-term exposure; concentrations less than 35 mg/l are likely protective during long-term exposures. Annex B of that same notice identifies two situations where the habitats are considered to be particularly vulnerable to the effects of road salt: Areas where the addition of road salts has the potential to harm a habitat necessary for the survival or recovery of a wildlife species listed on the List of Wildlife Species at Risk (Schedule 1 of the Species at Risk Act) where the area is identified as the species' critical habitat in the recovery strategy or in the action plan for the species established under that Act Areas where the addition of road salts has the potential to raise the chloride concentration, after mixing, to levels that could harm local fish or fish habitat (tremaine_dundas subwatershed study september_2009.doc)

43 Currently, there is no viable technology for the removal of chlorides from stormwater. Therefore, the only possibility of controlling chloride levels in stormwater discharges to natural watercourses is to consider management of chloride application during road maintenance activities. The Environment Canada notice dictates that in an area where vulnerable areas have been identified, that the municipality should: prepare and implement a salt management plan that contains best management practices to protect the environment from the negative impacts of road salts. It is recommended that the City of Burlington develop a salt management plan that recognizes the vulnerable areas. The creeks containing redside dace survival habitat are of paramount concern due to the fact that the redside dace is listed under Schedule 1 of the Species at Risk Act as an endangered species. However, in using the criteria of the Environment Canada notice, all streams identified as having resident fish populations and/or providing aquatic habitat should be considered as vulnerable to road salt, as the application of road salt has the potential to raise concentrations in these streams to toxic levels. It is therefore recommended that the salt management plan consider the entire planning area as vulnerable, and that the most up to date Best Management Practices be prescribed for this area within the salt management plan Stormwater Management Pond Locations The recommended locations of SWM ponds are illustrated in Figure This figure shows the selected land use plan, including areas for SWM ponds and the NHS lands. The location and sizing of the SWM ponds are based upon the principle of maintaining existing drainage patterns. The maintenance of existing drainage patterns is one of the principles and recommendations of this study to maintain flow regime conditions in the receiving system. Drainage boundaries are illustrated in Figure The locations are set to maintain current drainage outlets to existing watercourses so that flow regime conditions will be maintained in the receiving open streams. This is consistent with the goals and objectives set for the TSPSDA from a subwatershed perspective. In one particular area, however, the diversion of a sub-drainage area is proposed. As illustrated in Figures and 5.3.2, the sub-drainage areas FM 1102b and c (shown on Figure 4.1.1) are to be diverted to the SWM pond at the corner of Dundas Street and Tremaine Road. It is judged that this will not impact on the receiving watercourses for the following reasons: The watercourses downstream of Tremaine Road, for these particular sub-drainage areas, are to be piped, as recommended in the North Oakville Creeks Subwatershed Study; The corresponding tributary downstream of Dundas Street is to be piped as per the Fourteen Mile Creek Subwatershed Study, and The corresponding tributary joins Fourteen Mile Creek very close to Dundas Street (approximately 250m). From an environmental perspective, it is judged that the impact of the proposed flow diversion (to FM-D2 to FM-D1) on environmental conditions (aquatic and terrestrial) will not be significant. From a fluvial geomorphologic standpoint, the 250m section of watercourse downstream of FM-D1 is relatively flat sloped, with no defined valley, with vegetation indicative of wet conditions. As such the watercourse is vegetation controlled and resilient to increases in flow conditions. Accordingly it is (tremaine_dundas subwatershed study september_2009.doc)

44 FM2 Highway 407 FM3 Tremaine and Dundas Secondary Plan Subwatershed Study Legend Culvert Watercourse Study Area Boundary Bronte Creek Provincial Park Wetlands Tremaine Rd Bronte Creek Meters Existing Watercourse Conditions FM-D2 Dundas St Datum: NAD 83, Zone 17 Source: Town of Oakville 1:7,000 September 2009 Figure G:\Prj22600\ Tremaine Subwatershed Study\GIS\Report Maps FM-D1