Recommended biological and water quality limits for streams and rivers managed for contact recreation, amenity and stock drinking water in the

Transcription

1 Recommended biological and water quality limits for streams and rivers managed for contact recreation, amenity and stock drinking water in the Wellington Region March 2013

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3 Recommended biological and water quality limits for streams and rivers managed for contact recreation, amenity and stock drinking water in the Wellington Region March 2013 Report prepared for Greater Wellington Regional Council by: Dr Olivier Ausseil Principal Scientist Water Quality, Aquanet Consulting Limited Peer-review: Dr. Ned Norton, NIWA Prof. Gillian Lewis, School of Biological Sciences, Acknowledgments to: Summer Greenfield, Senior Environmental Scientist, Water Quality & Freshwater Ecology; Juliet Milne, Team Leader, Environmental Science Greater Wellington Regional Council Revision Schedule: Revision N. Date Description Reviewed by 1 June 2011 First draft Summer Greenfield, Juliet Milne 2 February 2012 Second draft Summer Greenfield, Juliet Milne 3 July 2012 Final draft Prof. Gillian Lewis; Dr Ned Norton 4 March 2013 Final Report - Cover photograph: Swimmers in the Waikanae River near Makora Road, 7 February Taken by Summer Greenfield.

4 EXECUTIVE SUMMARY Greater Wellington Regional Council (GWRC) is in the process of developing technical recommendations to support its second generation Regional Plan. This report makes recommendations relating to biological and water quality limits for waters managed for contact recreation, amenity and stock drinking water values in streams and rivers. This report is one in a series of technical reports on the Wellington region s streams and rivers, destined to inform and support the policy development process. It should be read in conjunction with the other reports in the series, which recommend biological and water quality limits in relation to aquatic ecosystem (Greenfield 2013a and 2013b; Ausseil, 2013b), and trout fishery values (Ausseil, 2013c). The report that recommends in-stream nutrient limits (Ausseil, 2013d) is also relevant to the periphyton limits recommended in this report for the protection of contact recreation values. The water quality limits recommended in this report for waters managed for contact recreation, amenity and stock drinking water are summarised in Table A below. The scope of application of these limits in GWRC s Regional Plan has yet to be defined. In particular, where and when each specific management purpose (including primary and secondary contact recreation, visual use, and stock drinking water) needs to be determined, so that the different limits recommended in this report can be applied to the relevant waterbodies. Table A: Summary of recommended water quality limits in relation to the contact recreation (CR), amenity (A) and stock drinking water (SW) management purposes. Water quality determinand E. coli ph Other irritants/toxicants Water clarity Periphyton cover Macrophyte cover Heterotrophic growths Management purpose Recommended limits 260/100mL at flows below median flow during the main bathing season; CR 550 /100mL at flows between median and 3x median flow during the main bathing season; 550 /100mL at flows below 3 x median flow outside the main bathing season; SW 550/100mL, applicable at flows below 3x median flow CR 6.5 to 8.5 SW 6.0 to 9.0 CR, SW CR, A CR, A CR, A CR, A Refer to ANZECC (2000) Guidelines (extensive list of chemicals, including metals/metalloids, organic contaminants/pesticides and associated guideline concentrations) 1.6m at flows below median flow 20% change at or near CR or amenity sites of high use 33% change in all other waters managed for CR or amenity 30% cover (filamentous algae>2cm long) 60% cover (mats >3mm thick) 30% cover as emergent macrophytes 60% cover as total macrophytes no bacterial or fungal slime growths visible to the naked eye as plumose growths or mats i

5 CONTENTS Table of Contents 1. Introduction Background Aim and scope of this report Policy context RMA National Policy Statement Freshwater Management Greater Wellington s proposed Regional Policy Statement Other regional policy statements and regional plans Biological and water quality limits Management purposes Data and methods Recreational waters in the Wellington Region and general approach Determinands Recommended limits Microbiological water quality MfE/MoH guidelines Recommended microbiological water quality limits for recreational waters Recommended microbiological water quality limits for stock drinking water Assessment of compliance Current state of the resource Water clarity and colour Minimum water clarity Changes in water clarity and colour Notes on monitoring methods and compliance assessment Periphyton Recommended limits Current state of the resource Macrophytes Recommended limits Current state of the resource Heterotrophic growths ii

6 3.6. Deposited sediments Water ph Recommended ph limits for recreational waters Recommended ph limits for stock drinking water Other toxicants/irritants Conclusions and recommendations Summary of recommended limits Further work and investigations REFERENCES Tables Table 1: Summary of numerical water quality standards, guidelines or targets in water managed for contact recreation (CR) and/or stock drinking water (SW) in selected operative or proposed regional plans Table 2: Rivers and lakes with significant amenity and recreational values, as identified in Appendix 1, Table 15 of GWRC s proposed RPS (GWRC2010) Table 3: Summary of water quality determinands relevant to the contact recreation, amenity and stock drinking water purposes Table 4: MfE/MoH (2003) surveillance, alert and action levels for fresh waters Table 5: Summary of recommended water quality limits in relation to the contact recreation (CR), amenity (A) and stock drinking water (SW) management purposes iii

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8 1. Introduction 1.1. Background Greater Wellington Regional Council (GWRC) is in the process of developing technical recommendations to support its second generation Regional Plan. This report is one in a series of technical reports on the Wellington region s streams and rivers, destined to inform and support the policy development process. This report makes recommendations relating to biological and water quality limits for waters managed for contact recreation, amenity and live stock drinking water values in streams and rivers. Contact recreation means recreational activities that involve body contact with the water. These typically include swimming, waterskiing, canoeing/kayaking and fishing. Amenity values are varied and diverse, but have generally in common the visual use of the water bodies. The term limit is used here as a generic term to describe a numeric or narrative threshold that defines a particular state for a river or stream. The way in which these limits will be used in the Regional Plan is a policy decision and is outside the scope of this report. In particular, it is important to note that since this report was initiated, the form of GWRC's regional plan process has changed from a 'traditional' single stage plan process to a two-stage 'collaborative' process. It is expected the two-stage process will involve firstly a regional plan which will include river and stream objectives appropriate at a regional scale and secondly collaborative development of catchment or 'whaitua' based river and stream objectives and resource use limits. This means that some of the instream 'limits' identified in this report will be used to inform the first stage, i.e. the definition of regional scale river and stream objectives, while some will be considered during the collaborative 'whaitua' second stage. Identification of at what stage the limits proposed here will be considered is outside the scope of this report. This report should be read in conjunction with the other reports in the series, which recommend biological and water quality limits in relation to aquatic ecosystem (Greenfield, 2013a and 2013b; Ausseil, 2011b), and trout fishery values (Ausseil, 2011c). The report that recommends in-stream nutrient limits (Ausseil, 2011d) is also relevant to the periphyton limits recommended in this report for the protection of contact recreation values Aim and scope of this report The aim of this report is to recommend biological and water quality limits for the maintenance and protection of contact recreation, amenity and stock drinking water values in rivers and streams of the Wellington region. There are a large number of biological and water quality determinands that can influence the suitability of a water body for contact recreation and stock drinking water purposes. The scope of this report is to recommend limits in relation to: - Microbiological quality; - Water clarity and colour; - Irritants/toxicants including ph; - Visual/odour: periphyton cover, sewage fungus, hydrogen sulphide, etc. With regards to toxicants and irritants, it is not within the scope of this report to re-develop specific numerical thresholds. Rather, the intention is to provide adequate references to guideline documents. The numerical limits recommended in this report are defined without any in-depth analysis of GWRC s SoE or recreational water quality monitoring programmes data, as to a large extent, contact recreation and amenity requirements are not region-specific. The use of the regional data may be necessary at a later 1

9 stage to identify areas of compliance/non-compliance and, possibly, interim management targets, but this does not form part of the scope for this report. The recommendations relating to water quality limits for deposited sediments and toxicants (other than ammonia) are kept general in this report. Detailed examination of toxicant guidelines is undertaken as part of a separate project (Pawson and Milne, 2011). Since this report was initiated in 2010 and primarily written in 2010/2011, guidelines published after that time have not been considered in this report. This concerns in particular the sediment assessment protocols (Clapcott et al. 2011) and the review of the instream plant and nutrient guidelines (Matheson et al., 2012). Similarly this report does not reference or consider recent changes in Regional Plan provisions (such as summarised in Table 3) and/or recent technical work on water quality limits (e.g. Uytendaal and Ausseil, 2013). Limits relating to cyanobacteria and biotoxins are not covered in this report, and it is suggested that they should be developed after the interim national cyanobacteria guidelines for recreational fresh waters (MfE/MoH, 2009) are finalised. Information regarding the state of the resource with regards to cyanobacteria can be found in a number of recent reports published by GWRC (e.g. Milne and Wyatt, 2006; Warr, 2009; Ryan and Warr, 2010) Policy context RMA The purpose of the Resource Management Act (RMA) (1991) is to promote the sustainable management of the natural and physical resources. This particularly includes safeguarding the life-supporting capacity of [ ] water [ ] and ecosystems and avoiding, remedying or mitigating any adverse effect of activities on the environment. Some sections of the RMA relate specifically to the management of the water resource and the protection of aquatic ecosystems. Sections 70(1) and 107(1) set five narrative standards in relation to permitted and consented discharges to water or to land. These standards relate to different potential impacts of a discharge, ranging from visual impact to adverse effects on aquatic life, but also relate to the consumption of freshwater by farm animals. Section 69 enables the following approaches to rules relating to water quality: Section 69(1) refers to Schedule 3, which identifies 11 water classes, corresponding to management purposes. Of particular relevance to this report, are the CR (water managed for contact recreation purposes) and A (water managed for aesthetic purposes) classes. Schedule 3 defines a suite of numerical or narrative water quality standards for each class. Section 69(1) also gives a mandate to regional councils to use and apply these classes and narrative water quality standards in Regional Plans. Where a regional council is of the opinion that these standards are not adequate or appropriate, it may define more stringent or specific water quality standards; Section 69(2) allows a regional council to define new classes where it is not satisfied that the classes/standards defined in Schedule 3 provide for certain management purposes. In addition, Section 63(3) prohibits the setting of standards in a plan which result or may result in a reduction of the quality of the water in any waters at the time of the public notification, unless it is consistent with the purpose of the Act to do so. The narrative standards in Schedule 3 to the RMA provide guidance for the definition of water quality limits in the context of this work. Of particular relevance to this report, are the Contact Recreation and Aesthetics management purposes and standards. They read as follows: 5. Class CR Water (being water managed for contact recreation purposes) (1) The visual clarity of the water shall not be so low as to be unsuitable for bathing. 2

10 (2) The water shall not be rendered unsuitable for bathing by the presence of contaminants (3) There shall be no undesirable biological growths as a result of any discharge of a contaminant into the water. 10. Class A Water (being water managed for aesthetic purposes) The quality of the water shall not be altered in those characteristics which have a direct bearing upon the specified aesthetic values National Policy Statement Freshwater Management 2011 On 12 th May 2011, a National Policy Statement (NPS) for freshwater management was gazetted. The NPS s preamble defines a list of national values of fresh water, including animal drinking water and recreational activities. The NPS contains five main parts relating to: A. Water quality, B. Water Quantity, C. Integrated Management, D. Tangata whenua role and interests and E. Progressive implementation programme. In Part A. (Water quality), Objectives A1 and A2 set the overall objectives, whilst Policy A1 directs every regional council to establish freshwater objectives and set freshwater quality limits for all bodies of fresh water in their region. Policy A2 directs the regional councils to set targets where water bodies do not meet the freshwater objectives. As far as practicable, this report uses the specific vocabulary (e.g. objectives, limits and targets) in the context and meaning defined by the NPS. The text of Objectives A1 and A2 and policies A1 and A2 is reproduced below for use of reference. Objective A1 To safeguard the life-supporting capacity, ecosystem processes and indigenous species including their associated ecosystems of fresh water, in sustainably managing the use and development of land, and of discharges of contaminants. Objective A2 The overall quality of fresh water within a region is maintained or improved while: a) protecting the quality of outstanding freshwater bodies b) protecting the significant values of wetlands and c) improving the quality of fresh water in water bodies that have been degraded by human activities to the point of being over-allocated. Policy A1 By every regional council making or changing regional plans to the extent needed to ensure the plans: a) establish freshwater objectives and set freshwater quality limits for all bodies of fresh water in their regions to give effect to the objectives in this national policy statement, having regard to at least the following: i) the reasonably foreseeable impacts of climate change ii) the connection between water bodies b) establish methods (including rules) to avoid over-allocation. 3

11 Policy A2 Where water bodies do not meet the freshwater objectives made pursuant to Policy A1, every regional council is to specify targets and implement methods (either or both regulatory and non-regulatory) to assist the improvement of water quality in the water bodies, to meet those targets, and within a defined timeframe Greater Wellington s proposed Regional Policy Statement GWRC s proposed Regional Policy Statement sets the proposed directions for the management of natural resources in the region, including freshwater quality (GWRC, 2010). Of particular relevance to this work is: Policy 11 Regional Plans will establish limits for water quality, flows and water levels that safeguard aquatic habitats and ecosystems in water bodies. The narrative standard for aquatic ecosystems in the Third Schedule to the Resource Management Act will be used as the basis for safeguarding what is needed for aquatic ecosystem protection in terms of water quality. Policy 11 also indicates that some water bodies may also be managed for other purposes, such as trout fishery, contact recreation, water supply, groundwater protection or cultural purposes. Where more than one management purposes is assigned to a waterbody, water quality shall not be less than the limits established for aquatic ecosystem health Other regional policy statements and regional plans Most regional councils in New Zealand have produced regional policy statements and regional plans. Although most regional policy statements and regional plans identify management objectives and/or values associated with water bodies, only a relatively small number of regions have operative or proposed numerical water quality standards. One of the first regional plans to contain numerical water quality standards was the Manawatu Catchment Water Quality Regional Plan (MCWQ), which became operative in The MCWQ classifies all natural streams and rivers in the Manawatu catchment for contact recreation and defines a series of numerical water quality standards specifically for the protection of this value (Table 1). The Waikato Regional Plan (2007) defines a Contact Recreation Water Class and sets specific policies and water quality standards for this class. These are also summarised in Table 1. More recently, Canterbury s Proposed Natural Resources Regional Plan (April 2011 version) contains numerical water quality outcomes relating to the protection of contact recreation values. The Regional Water Plan for Southland (2010) contains water quality standards to avoid levels of contaminants in water and sediments that could harm the health of humans,[and] domestic animals including stock. The Manawatu-Wanganui combined Regional Policy Statement and Regional Plan, the Proposed One Plan, was notified in Submissions on the notified plan were heard and the panel decision released in August The Proposed One Plan (2010) includes a framework of 19 river values (ecological, recreational and cultural, consumptive use and social and economic values) and water quality targets, superimposed over a spatial framework constituted of 44 water management zones and 117 water management sub-zones. The Proposed One Plan values framework sets that the Contact Recreation and Stock Water values and associated numerical water quality targets apply to all natural water bodies in the region. Numerical targets are summarised in Table 1. The One Plan is currently under appeal to the Environment Court. 4

12 Table 1: Summary of numerical water quality standards, guidelines or targets in water managed for contact recreation (CR) and/or stock drinking water (SW) in selected operative or proposed regional plans. Region Plan Values Determinand Limit Comment Enterococci 33/100ml (median) 107/100mL (max) Standard apply at or below half median flows Sewage No visible growth Standard apply at or below half median flows Fungus Manawatu Periphyton 40% Catchment CR cover (filamentous >2cm) Periphyton standards are primarily associated with protection of contact Water Quality Periphyton 100 mg/m recreation values Regional Plan biomass (Chlorophyll a) Other The water shall not be rendered unsuitable for bathing by the presence of Narrative standard contaminants contaminants Manawatu- Water clarity 1.6m Standard apply at or below half median flows Wanganui 260/100mL Target applies to all natural waterbodies, under median flow E. coli Target applies to all natural waterbodies, under /100ml flow exceedance percentile 30% Periphyton (filamentous >2cm) One Plan CR cover (2010) Target applies to all natural waterbodies 60% (mats > 3mm) Water clarity 1.6m SW - - Catered for by CR E.coli standards Sewage Fungus No visible growth Target applies below median flow. Superseded by more stringent targets (associated with life-supporting capacity or trout fishery) in many water management zones. This standard applies to within the zone of reasonable mixing Southland Regional Water Plan for Southland CR SW E. coli 130/100mL In some water body classes, the CR standard applies to all water bodies, and supersedes the SW standard. In some other classes, the SW Faecal coliforms 200 /100mL (median) 1,000 /100mL standard applies to all waterbodies, and the CR standard applies only to Popular Bathing Sites defined in the plan Appendices 5

13 Region Plan Values Determinand Limit Comment SFRG 1 Fair to good Numerical objective depends on water body class. Some classes have no SFRG objectives Canterbury Periphyton 10 to 30% Natural Numerical objective depends on water body class cover (filamentous >2cm) Resources Periphyton 50 to 200 mg/m Regional Plan CR Numerical objective depends on water body class biomass (Chlorophyll a) (NRRP Macrophyte 20 to 30% (emergent) October 2010) Numerical objective depends on water body class cover 30 to 60% (total) Deposited sediment 10 to 40% cover Numerical objective depends on water body class Waikato Waikato Regional Plan (2007) CR (CR Water Class) E. coli 126/100mL (median) 235 /100mL (max) Based on dry weather sampling. Set as a standard for Contact Recreation Class Sewage Fungus No visible growth Set as a standard for Contact Recreation Class Periphyton 25% Set as a Policy (Policy 6) for Contact Recreation Class cover 40% Periphyton biomass 100 mg/m 2 (Chlorophyll a) Set as a standard for Contact Recreation Class Water clarity 1.6m Set as a standard for Contact Recreation Class Other The water shall not be rendered unsuitable for contact recreation Narrative standard contaminants activities by the presence of contaminants 1 Suitability For Contact Recreation Grade, a grading system based on the previous 5 years of data, as per the Microbiological Water Quality Guidelines for marine and freshwater recreational areas (MfE/MoH, 2003). 6

14 1.4. Biological and water quality limits Biological and water quality numerical thresholds can be expressed in a number of ways in regional plans: as objectives, limits, standards, targets or guidelines. The actual terms, and their applicability in different circumstances will be defined by the regional planning framework (RPS and Regional Plan). This report is a technical report, and it is outside its scope to make detailed recommendations regarding the policy framework. This report generally uses the term limits in relation to biological and water quality thresholds, although the use of these limits as actual standards directly applicable to consented activities is suggested where particularly relevant Management purposes Policy 11 in the proposed RPS indicates that water bodies shall be managed as a minimum for the purpose of maintaining or enhancing aquatic ecosystem health. Policy 11 indicates that some water bodies may also be managed for other purposes, such as trout fishery, contact recreation, water supply, groundwater protection or cultural purposes. Where more than one management purposes is assigned to a water body, water quality shall not be less than the limits established for aquatic ecosystem health. This report makes recommendations for biological and water quality limits in relation to the maintenance and/or protection of contact recreation, amenity and stock water values in the Wellington region. Under the current provisions of the proposed RPS, management purposes associated with recreational activities apply to identified water bodies and come in addition to the aquatic ecosystem management purpose. As a result, any biological or water quality limit defined in relation to the protection of contact recreation amenity and stock water values will only become applicable if it brings an additional level of protection to the waterbody. Where the limits defined in this report in relation to, say, contact recreation, are less stringent than those defined for the protection of aquatic ecosystems, they will be superseded by the aquatic ecosystems limits. More generally, the biological and water quality limits recommended in this series of technical reports in relation to different management objectives or values will have to be collated in order to present a coherent set of limits for each water body in the region. This exercise is outside the scope of this report. 2. Data and methods 2.1. Recreational waters in the Wellington Region and general approach The ANZECC (2000) guidelines define three categories of recreational activities, based on the frequency and intensity of body contact with the water: the activities in which the user comes into frequent direct contact with water, such as swimming and waterskiing (Primary Contact); the activities that generally have less-frequent body contact with the water, such as boating and fishing (Secondary Contact); and Activities occurring in close proximity to the waterbody but that do not involve direct contact with the water, such as walking (Visual Use). GWRC s proposed RPS identifies water bodies with significant amenity and recreational values (Table 2). It is outside the scope of this report to undertake an assessment or a review of where the contact recreation or stockwater management purposes should, or should not apply. To a large extent, the definition of water quality limits for waters managed for contact recreation or stock drinking water purposes is not site-specific. The approach taken in this report is to define generic limits without specifying the water bodies where such limits may, or may not, apply. 7

15 However, the recreational uses listed in Table 2 can easily enough be categorised as involving primary contact (e.g. swimming, tubing, etc ), secondary contact (e.g. fishing, canoeing, etc ) or visual use only (walking, running, etc..). These management purposes follow a hierarchy, i.e. primary contact also by default includes secondary contact and visual use, and secondary contact also includes visual use. To provide a degree of flexibility, and allow for precise fitting between the management purposes and recommended limits for each waterbody, this report identifies whether each limit should apply to all waters managed for recreational or amenity purposes, or only to waters managed for primary or secondary contact. Generally speaking, peak primary contact use is expected to occur during the warmer months of the year. The MfE/MoH (2003) guidelines for recreational waters mention that the bathing season will generally extend from 1 November to 31 March. Secondary contact activities, such as boating, kayaking or fishing and visual use are less restricted to the warmer months of the year and are considered year-round activities for the purpose of this work. With regards to stream and river flows, peak primary contact use is expected to occur during periods of stable or low flows, whilst secondary contact is likely to occur at all but flood flows. Periods of high river flows are unlikely to be periods of high contact recreation use, due to unpleasant weather, discoloured/turbid waters and high water velocities, making the contact recreation experience unpleasant or unsafe. Of course visual use occurs at any time, but public expectations with regards to the visual appearance of rivers generally depend on location and conditions. For example, one generally expects clearer water during low river flows, but more turbid waters during a flood. The water quality limits defined in relation to the recreational use of water bodies recommended in this report account for these considerations. Table 2: Rivers and lakes with significant amenity and recreational values, as identified in Appendix 1, Table 15 of GWRC s proposed RPS (GWRC2010). River or lake Lake Waitawa (Forest Lakes) Otaki River Waikanae River Kaiwharawhara Stream Korokoro Stream Hutt River Pakuratahi River Akatarawa River Upper Gollan s Stream (including Butterfly Creek) Wainuiomata River Orongorongo River Kohangapiripiri and Kohangatera Lakes Ruamahanga River Tauherenikau River Waingawa River Waiohine River Kopuaranga River Waipoua River Henley Lake, Masterton Lake Wairarapa Recreational uses kayaking, windsurfing, sailing fishing, swimming, kayaking, canoeing, tubing, rafting, picnicking, camping fishing, swimming, camping picnicking, walking, running walking, running, mountain biking fishing, swimming, kayaking, canoeing, tubing, rafting, power boating, radio controlled boats, jet skis, picnicking, walking, running, mountain biking fishing, swimming, picnicking fishing, swimming, kayaking, bird watching, picnicking, walking, running, mountain biking, trail biking, horse riding, 4-wheel driving picnicking, tramping walking, running, bird watching fishing, swimming, canoeing, kayaking, walking, horse riding fishing, tramping bird watching, picnicking, walking, mountain biking fishing, swimming, kayaking, canoeing, tubing, rafting, power boating, jet skiing, picnicking, walking, duck shooting fishing, swimming, walking, picnicking, rafting fishing, swimming, kayaking, tubing, rafting, walking fishing, swimming, kayaking, canoeing, tubing, rafting, camping fishing fishing, swimming, running, trail biking kayaking, dragon boating, radio controlled boats, picnicking, running, biking fishing, kayaking, canoeing, boating, duck shooting, bird watching, walking, photography 8

16 2.2. Determinands A large number of measurable biological, water quality and habitat determinands are relevant to the protection of contact recreation and stock drinking water values in streams and rivers. The scope of this report is to include the determinands most commonly associated with these values, and point to guideline documents that contain more complete lists of determinands, for future reference in particular cases. Table 3summarises the determinands selected, the management purpose(s) they apply to, and the reasons for their selection. It is noted that, to a large extent, this list of determinands is consistent with those recommended by Hayward et al. (2009), Ryder (2004) and Ausseil and Clark (2007b) for the protection of contact recreation and stock drinking water values in the Canterbury, Southland and Manawatu- Wanganui regions respectively. Table 3: Summary of water quality determinands relevant to the contact recreation, amenity and stock drinking water purposes. Main issue Microbiological water quality Irritants / Toxicants Visual / aesthetic aspects Water quality determinand Management purpose E. coli CR FC SW Notes Used as an indicator of health risk to water users. Primary reference document for this report is the 2003 Microbiological Water Quality Guidelines for marine and freshwater recreational areas (MfE/MoH, 2003) Used as an indicator of health risk to stock. ANZECC (2000) guidelines ph CR, SW Very low or high ph can cause skin/eye irritation. Other irritants/ toxicants Water clarity CR, SW CR, A Refer to ANZECC (2000) guidelines (extensive list of chemicals, including metals/metalloids, organic contaminants/pesticides and associated guideline concentrations) Can affect aesthetic values, but also safety aspects (some degree of water clarity is preferable to judge depth and see underwater obstacles) Water colour CR, A Can affect aesthetic values Periphyton cover CR, A Can affect aesthetic values and suitability for contact recreation Macrophyte Can affect aesthetic values and suitability for contact recreation CR, A cover Can also impede water flow Heterotrophic growths CR, A Can affect aesthetic values and suitability for contact recreation Films, scums, foams CR, A Can affect aesthetic values and suitability for contact recreation Hydrogen Odour causing ( rotten egg ). Can affect aesthetic values and CR, A sulphide suitability for contact recreation Other odour causing CR, A Can affect aesthetic values and suitability for contact recreation 9

17 3. Recommended limits 3.1. Microbiological water quality MfE/MoH guidelines The MfE/MoH (2003) guidelines define a three-mode management system for recreational beaches, with a traffic light colour-coding system (Table 4). The guidelines recommend that this system be applied during the main bathing season. The green mode corresponds to a low level of health risk to recreational users of the water body. The amber mode is indicative of a slightly more elevated, yet still acceptable, health risk (for freshwaters the acceptable level of risk is 8 in every 1,000 bathers). The red mode means that the health risk to swimmers is unacceptably elevated, and the site/beach is considered unsuitable for swimming. At this point, the MfE/MoH (2003) guidelines recommend that warning signs be erected, monitoring frequency be increased and investigations into the source of pollution be conducted. Table 4: MfE/MoH (2003) surveillance, alert and action levels for fresh waters. Mode Guideline E. coli (cfu/100 ml) Green/Surveillance Single sample 260 Amber/Alert Single sample > 260 and 550 Red/Action Single sample > 550 Management Response Routine monitoring Increased monitoring, investigation of source and risk assessment Closure, public warnings, increased monitoring and investigation of source The influence of high rainfall on the microbiological water quality monitoring results is well established in the Wellington Region. For example, during the 2009/2010 bathing season, 18 routine monitoring results from the recreational water quality monitoring programme fell into the Red/Action mode. All of these 18 samples were associated with rainfall events of 10mm or more (Ryan and Warr, 2010). The same pattern has been identified in other regions, including the Manawatu-Wanganui Region, and was one of the reasons why the water quality limits recommended for the Proposed One Plan for the protection of the contact recreation value specifically excluded periods of high river flows (Ausseil and Clark, 2007b). For this reason and those laid out in section 2.1 of this report, a similar approach is recommended here Recommended microbiological water quality limits for recreational waters Based on the MfE/MoH (2003) guidelines and the above considerations, the following limits are recommended for inclusion into the GWRC s Regional Plan: Sites managed for primary contact, secondary contact and amenity: 260 E. coli /100mL when river flows are at or below median flows during the main bathing season; 550 E. coli /100mL when river flows are between median flow and 3x median flow during the main bathing season; 550 E. coli /100mL when river flows are at or below 3x median flow outside the main bathing season. 10

18 Sites managed for secondary contact and amenity: 550 E. coli /100mL when river flows are at or below 3x median flow. Sites managed for amenity only: No microbiological water quality limits required. The Suitability For Recreation Grade (SFRG) is the recreational beach grading system recommended in the MfE/MoH (2003) guidelines. Assuming that they are met at least 95% of the time, the limits recommended in this report broadly equate to managing: the sites managed for primary contact recreation in the Good to Very Good SFRG categories under median flow during the bathing season; and the sites managed for secondary contact recreation, and the sites managed for primary contact recreation outside the bathing season in the Fair (assuming a very low to moderate Sanitary Inspection Category - SIC) or better (Good or Very Good) categories Recommended microbiological water quality limits for stock drinking water The 2000 ANZECC guidelines recommend that drinking water for livestock should contain less than 100 faecal coliforms (FC) per 100 ml (as a median) and less than 400 FC/100mL as an 80 th percentile. However, there is considerable debate about the validity and applicability of this guideline, including: FC analysis includes bacteria of non-faecal origin, such as Enterobacter, Citrobacter and Klebsiella. The common occurrence of false positive results is one of the reasons why E. coli is now generally the preferred indicator of faecal contamination in freshwater; The 100 FC/100mL threshold is quite stringent and would be expected to be exceeded in many situations, including in relatively natural situations (false- positive detection, as above). For this reason, a lot of Regional Councils have reverted back to the 1992 ANZECC stock drinking water guideline of 1,000 FC/100mL for general reference use in, for example, State of the Environment reports; Defining a guideline based on FC in relation to stock drinking water would present the disadvantage of requiring monitoring of both FC and E. coli (for contact recreation), hence doubling the costs to essentially assess the same issue, i.e. that of faecal contamination. To address these issues, it is recommended to use E. coli as the indicator of faecal contamination in relation to both contact recreation and stock drinking water management purposes. This is consistent with the recommendations of Wilcock (2009) for inclusion in the Manawatu-Wanganui One Plan. Wilcock (2009) also recommended that stock drinking water values would be adequately protected by the Red/Action mode threshold for recreation of 550 E. coli/100ml. This seems a pragmatic recommendation by a recognised expert, and a similar limit is recommended for GWRC s Regional Plan. For consistency with the Contact Recreation limits recommended above, it is recommended that this limit apply at river flows at or below 3x median flow Assessment of compliance The Suitability For Recreation Grade (SFRG) grading system recommended in the MfE/MoH (2003) guideline is based on the comparison of the 95 th percentile of the data collected at a given site with numerical thresholds. To maintain consistency with the MfE/MoH guidelines, it is recommended that the 11

19 overall compliance of a site with the E. coli concentration limits recommended in this report be assessed against the 95 th percentile of the data Current state of the resource A detailed assessment of the current state of the resource is outside the scope of this report. However, GWRC has produced a number of publications that summarise microbiological water quality monitoring results, and the reader is invited to refer to these publications (Milne, 2005; Milne and Wyatt, 2006; Ryan and Warr, 2008; Warr, 2009; Ryan and Warr, 2010, Morar and Warr, 2011) and is also currently preparing a comprehensive analysis of the last five years of recreational water quality monitoring results as part of its five-yearly State of the Environment reporting Water clarity and colour Water clarity and colour are of considerable importance for the protection of contact recreation values, because they are directly perceived by recreational water users, and directly affect the aesthetic quality of the water. In addition, visual clarity is also important so that swimmers can estimate depth and see subsurface hazards (ANZECC, 2000) Minimum water clarity The ANZECC (2000) guidelines and the 1994 MfE (1994) Water Quality Guidelines No.2 both recommend that the water clarity of recreational waters should not be less than 1.6 metres. This numerical limit has since been widely used in New Zealand in regional plans, resource consent processes and reporting (such as state of the environment reporting), and is recommended as a numerical limit for streams and rivers managed for contact recreation. Water clarity affects all aspects of recreational use of waterways: primary and secondary contact and visual use. To protect the visual use of lakes and coastal waters, the recommended limit should apply year-round. In rivers, the limit should apply under median flow during the bathing season to protect primary contact recreation. Visual use of rivers and streams occurs year-round, at all river flows. However, most rivers are naturally turbid during high river flows, and would be expected to breach the 1.6 m limit at least occasionally. It is suggested that relatively clear water during periods of base flow constitutes a reasonable expectation, and it is recommended the minimum water clarity limit of 1.6m apply year-round, when the river flow is at or below the median flow Changes in water clarity and colour The RMA Sections 70 and 107 standards set that discharges of contaminant into water shall not give rise to any conspicuous change in the colour or visual clarity in the receiving waters. The MfE (1994) Water Quality Guidelines No. 2 provide guidance as to what degree of water clarity change constitutes a conspicuous change : 20% change in waters where visual clarity is an important characteristic of the water body, and 33% to 50% in other waters. Panel studies have shown that most people can detect a change of 30% in visual clarity (Davies-Colley and Smith, 1990). As indicated above, water clarity not only influences the aesthetic, but also safety aspects of contact recreation, and it is postulated that water clarity is an important characteristic for waters managed for contact recreation, particularly at or around sites that receive heavy public use. The following limits setting maximum change in water clarity as a result of a given activity are recommended: 20% water clarity change at, or near identified high use contact recreation or amenity sites or reaches; 12

20 33% water clarity change in all other waters managed for contact recreation. It is expected that water clarity change limits will adequately cover potential issues associated with changes in water colour and euphotic depth, except in exceptional cases (Davies-Colley, 2010). Exceptional cases where an activity may affect water colour or euphotic depth whilst complying with the clarity change standard should be assessed on a case-by-case basis. No specific limits relating to water clarity or colour are recommended for waters managed for stock water drinking Notes on monitoring methods and compliance assessment The most common method of measuring visual clarity in rivers in New Zealand is by measuring the horizontal sighting range of a black disc (Davies-Colley, 1988). It is a simple field method that can be used to directly estimate the beam attenuation coefficient, the primary factor controlling underwater visual ranges for both humans and aquatic animals (Davies-Colley, 1988; Davies Colley et al., 2003). The direct black disc measurement can be limited by high turbidity and/or physical conditions at the sites (e.g. very small, shallow streams). In these cases, visual clarity can be measured ex-situ in a steel trough. These measurements have been shown to be closely correlated with both in-situ measurements and the beam attenuation coefficient (Davies-Colley and Smith, 1992). Another out-of-stream method uses a 1m long clear plastic tube, with a small black disc sliding inside the tube. This method was originally developed as part of the Stream Health Monitoring and Assessment Kit (SHMAK) (Biggs et al., 2002). The clarity tube measurements have been shown to be correlated with insitu clarity measurements, particularly in relatively low water clarity environments (Kilroy and Biggs, 2002). Nephlometric turbidity provides a relative measure of light scattering and has no direct environmental relevance (Davies-Colley, 1991). Turbidity and water clarity and turbidity and total suspended solids are generally well correlated, although specific relationships vary between rivers. Turbidity probes can be directly installed on site and provide a continuous turbidity record. Continuous turbidity monitoring can be a very useful way of providing a continuous (including at night) assessment of compliance with water clarity limits, provided that specific turbidity/water clarity relationships are established at each site. All three methods above are acceptable as surrogates for direct visual clarity measurements, within their respective field of application, and it is recommended that any Regional Plan limit or standard allow for the use of these methods as dictated by conditions. Compliance with the recommended limits should be assessed at 80% compliance level, and should apply under base flow conditions, i.e. under median flow conditions. In other words, a site will be deemed to comply with the recommended limit if 80% or more of the measurements undertaken at this site when the flow is below median flow are better than the recommended limit. The RMA S107 and S70 standards relating to conspicuous change in water colour or clarity do not specify any acceptable frequency or duration of breach of these standards. The recommended water clarity change limits may thus be applied to single water clarity measurements. It is noted however, that specific situations may require a modification or relaxation of this limit. For example, in situations where a conspicuous change in water clarity is inevitable as the result of an activity (e.g. infrastructure works in the bed of a river), then a duration or frequency at which the limit may be breached may need to be defined (e.g. 8 hours in a row, or 2 hours after the cessation of the works). 13

21 3.3. Periphyton Recommended limits Excessive periphyton growth can have detrimental effects on the visual and aesthetic values of streams and rivers. The New Zealand Periphyton Guidelines (Biggs, 2000) define numerical periphyton biomass and cover guidelines for the protection of aesthetic/recreation values. A maximum biomass of 120 mg chlorophyll a /m 2 for filamentous algae; and A maximum of 30% bed cover by filamentous algae more than 2 cm long; and A maximum of 60% bed cover by diatoms/cyanobacteria mats more than 3 mm thick. The percentage of bed cover is a visual measurement and is directly relevant to the protection of recreational and aesthetic values of rivers and streams. The above periphyton cover guidelines are recommended as limits for streams and rivers managed for contact recreation in the GRWC Regional Plan. As part of the wider work stream currently undertaken in relation to the definition of recommended biological and water quality limits for GWRC s Regional Plan, periphyton biomass limits are being recommended for the protection of Aquatic Ecosystem (Greenfield, 2013b) and trout fishery values (Ausseil, 2011c). These biological limits take into account the natural characteristics of the different classes of rivers and streams in the Wellington Region. It is expected that these limits will adequately protect the recreational/aesthetic values of the waterbodies at the same time as the Aquatic Ecosystems and Trout Fishery values, and additional periphyton biomass limits specifically for the Contact Recreation value would be largely redundant and are not recommended. No specific limits relating to periphyton are recommended for waters managed for stock drinking water Current state of the resource Periphyton cover is currently visually assessed as part of two of GWRC s regular monitoring programmes: the River State of the Environment (RSoE) programme (monthly) and the contact recreation (CR) monitoring programme (weekly in summer). Data from both programmes are very useful in characterising the state of the resource, both directly at sites used for contact recreation (CR programme) and in a wider sense across the region. The results of both programmes are summarised in recent reports by Ryan and Warr (2010), Morar and Warr (2011) for the CR monitoring programme, and Ausseil (2011a) for the SoE monitoring programme. It is also noted that Ausseil (2011a) recommends that the visual periphyton cover method used in the RSoE monitoring programme be reviewed, to be better aligned with the assessment method used as part of the CR monitoring programme, as this is a more detailed method involving the assessment of riffle habitat in addition to run habitat Macrophytes Recommended limits Macrophytes (aquatic vegetation that can be observed by the naked eye), are a natural and normal part of the stream ecosystem, and play a particularly significant role in streams where the bed substrate is dominated by fine/soft sediment, such as sand, silt and mud. They play beneficial roles in some stream environments by increasing physical heterogeneity, trapping fine sediment and providing habitat for periphyton, macroinvertebrates and fish. However, just like periphyton, macrophytes can proliferate to nuisance levels and cause detrimental effects on aesthetic and recreational stream values and water 14

22 quality, by affecting ph and dissolved oxygen (Hayward et al. 2009). Heavy macrophyte growth can also impede water flow, particularly in small streams with stable flow. Macrophyte biomass and cover have not been formally monitored as part of the RSoE or the CR monitoring programmes. However, the presence of macrophytes, particularly when heavy growth is observed is informally recorded as part of the RSoE monitoring programme. GWRC s staff have identified that 8 RSoE sites present regular nuisance macrophyte growth, and that an additional 3 sites present either regular moderate growth, or infrequent nuisance growth. Of the 10 RSoE sites that are softbottom dominated, 5 (50%) present significant or moderate issues associated with macrophyte growth. On the basis of evidential, although anecdotal, information relating to the existence of significant issues associated with excessive macrophyte growth in the Wellington Region, the setting of limits relating to macrophyte growth is recommended for GWRC s Regional Plan. Although issues associated with macrophyte growth are commonly acknowledged in many other regions in New Zealand, there do not appear to be any current national guidelines relating to macrophyte cover or biomass. A three-phase Envirolink funded review of instream plant and nutrient guidelines is currently being undertaken. It is intended that the second phase of this review (due June 2012) will provide guidance on macrophyte assessment methods and protocols and acceptable levels of macrophyte abundance for different management purposes. A method based on the measurement of macrophyte volume (rather than cover) is likely to be recommended. To date, the Canterbury NRRP is the only regional plan in New Zealand to set numerical limits relating to macrophyte growth. These limits were originally based on the recommendations of Hayward et al. (2009), and are expressed as percentage cover of stream/river bed, as emergent macrophytes (20 to 30% cover) and total macrophyte (30 to 60% cover). These limits apply to stream/river classes where bed substrate is generally dominated by soft sediment (i.e. spring-fed streams in the Canterbury Region). The Canterbury NRRP limits were defined on the basis of macrophyte cover data collected by Environment Canterbury. Such data does not exist in the Wellington Region, and expert opinion is therefore the best option available to base recommendations on. On this basis, annual maximum limits of 30% emergent macrophyte cover and 50% total macrophyte cover are recommended as interim limits for streams and rivers managed for contact recreation and amenity purposes. These interim limits can be applied across the board, but will be particularly relevant to streams and rivers where physical and hydrological characteristics are suitable for macrophyte development, particularly spring-fed and soft-bottomed streams. It is recommended that these interim limits be reviewed upon release of the review of instream plant and nutrient guidelines. No specific limits relating to macrophytes are recommended for waters managed for stock drinking water Current state of the resource As indicated above, macrophyte abundance has not historically been formally assessed as part of GWRC s RSoE or recreational water quality monitoring programmes. GWRC have recently started monitoring of macrophyte volume at both RSoE and CR sites, following a method being trialled as part of the review of instream plant and nutrient guidelines. Data from these programmes should be used in the future to assess the existence, extent and severity of issues associated with macrophyte growths across the region, and to validate or refine the numerical thresholds recommended in this report. 15