How To Manage Waterways

Transcription

1 35 3 Key values our waterways support 3.1 Threats to values Amenity Birds Fish Frogs Macroinvertebrates Platypus Vegetation 49

2 An understanding of waterway value requirements and condition is important information underpinning our work to improve the condition of waterways. This chapter describes the key values that are the focus of the Healthy Waterways Strategy and the basis of our target framework. It outlines some of the main threatening influences to the key values, how their condition has been measured and provides conceptual models for the relationship between the values and potential management actions. Key values directly link the outcomes of management actions and programs to the vision. That is, we undertake management actions to protect and improve the condition of waterways so they can support values. Research and consultation tells us that these key values amenity, birds, fish, frogs, macroinvertebrates, platypus and vegetation are the main reasons that the community wants to protect and improve waterways. By assessing the condition of key values over time, we can understand how successful management actions have been in improving conditions that support waterway health. For each of the key values, a method to measure condition has been developed to make best use of the available data. Some of the measures are limited by the data available. Throughout the life of the strategy we will explore ways to improve measurement of condition (for example, developing a standard biomass measure for fish) and ensuring we have enough samples to be confident in measuring condition. Although we measure key values to understand how successful our works have been, most of our works are designed to achieve multiple benefits including social and economic, as well as environmental. The chapter also describes the aspects of waterway condition (e.g. water quality, habitat, flows) that are critical to supporting key values and what management actions are needed to create these favourable conditions. The management actions are described in terms of riverine (streamside) or floodplain quality and connectivity to indicate if the action is applicable to the waterway itself or to the land adjacent. This information is presented in a conceptual model for each value (for an explanation of conceptual models, see Box 2.3: Conceptual models). The conceptual models are generic for each value. The primary influences in one specific location can be of less importance in another. For example, litter is considered one of the most important threatening influences on platypus in the Werribee catchment, whereas in the Dandenong catchment the lack of connectivity between habitat zones has a greater influence on platypus health. These models capture our understanding of relationships between values and waterway condition, however local considerations are applied to these conceptual models when designing and implementing management actions. To understand how other values related to waterways are managed, see Chapter 2: Identifying key values. More details on the condition assessment and how priority areas were identified for each value can be found in the Healthy Waterways Strategy Resource Document. Confluence of Steeles Creek and Maribyrnong River 36 Healthy Waterways Strategy 2013/ /18 Chapter 3: Key values our waterways support

3 3.1 Threats to values Some of the most significant threats to waterway values are: Changes to natural water flows. Many fish rely on a particular level of flow at the right time of year to trigger breeding; modifications to the natural flow regime can have significant impacts. Very low flows can lead to a reduction in habitat for values including platypus, frogs and fish, and very high flows can destroy important in-stream habitat and features such as pools and small rapids. Poor water quality. Pollutants such as pesticides, pathogens, excess sediment and heavy metals threaten environmental values. Litter and unpleasant smells and odours detract from social values. Vegetation clearing. Vegetation removal decreases bed and bank stability, reduces feeding and breeding habitat for environmental values, changes the temperature and light within streams, which affects biodiversity, aquatic habitat, and the sense of naturalness that contributes to amenity. Pest plants and animals. Pest animals threaten all environmental values. Foxes, feral dogs and cats prey on birds, reptiles and mammals including platypus. Grazing and browsing animals such as rabbits and deer reduce the cover of indigenous plants and prevent the establishment of new plants. Pest plants displace indigenous vegetation. Reductions in indigenous vegetation can have a profound impact on the healthy functioning of waterways. Urbanisation. As vegetated surfaces are replaced with hard impervious surfaces (such as roofs, roads and paved areas) that drain directly into waterways via stormwater systems, there are increases in runoff (changed water flow rates) and reduced water quality. Urbanisation also results in altered waterway structure, with rivers straightened, wetlands drained, estuaries artificially opened, vegetation cleared and predators such as dogs and cats introduced. Climate change. Different scenarios will affect waterway health in different ways. Predictions of longer intervals between rain, and more intense rainfall will affect water quality. In particular areas, it is predicted that some waterways will become dry for longer, resulting in the loss of habitat for certain species of macroinvertebrates and fish. Drying conditions also result in increases in salinity this is a concern particularly in the west of the region. In other scenarios, more frequent intense rainfall will change waterway structures and habitat availability. A summary of the threats for each value is included in the Healthy Waterways Strategy Resource Document. 3.2 Amenity The attributes that contribute to the way people appreciate and value waterways can be tangible, such as paths and natural vegetation, or intangible such as vistas, links to places or people or the knowledge that wildlife is present. Amenity is the pleasantness, attractiveness or agreeable nature of a place. The Healthy Waterways Strategy defines amenity as the pleasantness of a waterway to visitors and the ability of the waterway to provide a restorative escape from the urban landscape. Amenity derived from waterways is intrinsically linked to the quality and extent of the natural vistas, vegetation and natural surroundings. Physical aspects such as the sight and sound of running water, accessibility to an area, the ability to move along or around a waterway, and facilities that enable time to be spent beside waterways are also important. Amenity values are diminished by the presence of unpleasant or intrusive development, odour, litter, and noise. Amenity means different things to different people, but is the most commonly expressed reason for visiting waterways and is an important value that needs to be managed and protected. The Department of Sustainability and Environment s 2009 My Victorian Waterway survey assessed how Victorians relate to waterways and found that 92% of people visit waterways to enjoy the scenery. This is consistent with the results of research in our region showing that passive activities at waterways are more popular than active recreation. Melbourne Water does not have responsibility for providing recreational assets, but we support good recreational outcomes on and beside waterways where they do not conflict with waterway function or environmental values. Other stakeholders such as local government have an active role in planning for and providing recreational facilities. For an overview of how amenity was selected as the key social value for the Healthy Waterways Strategy, see Box

4 The amenity values of waterways contribute to our wellbeing The amenity values of waterways contribute to the general wellbeing of individuals and communities including relieving stress and emotional and mental fatigue often described as their restorative nature. The community places a high value on areas to relax and replenish, and these areas enable a sense of connectedness to others and to nature. The sense of amenity provided by waterways varies in different settings. For example, forested headwaters provide a sense of naturalness and urban escape but often do not have facilities such as tables, seats or toilets. Conversely, urban parks have more open space and facilities such as bicycle paths and picnic tables, which offer a different type of experience. Melbourne Water is a key contributor to the creation and maintenance of the waterway setting that provides amenity through management of the waterway channel and of vegetation along waterways. Often works undertaken to improve amenity, such as revegetation, will have positive outcomes for other values and vice versa. Melbourne Water will not undertake works to improve amenity if they are to the detriment of environmental values. BOX 3.1 Refining our understanding of social values amenity The social value of waterways has long been recognised as important. Research commissioned by Melbourne Water, the previous Melbourne Parks and Waterways, and then Department of Sustainability and Environment have established that people feel that waterways are places of value where they can undertake passive and active recreation. In the RRHS, Melbourne Water had an aim to improve social value. In developing the Healthy Waterways Strategy, we have undertaken additional analysis to refine the social target to focus on amenity. A review of literature, discussion with internal experts and analysis of recent social research identified four potential social values: recreation, amenity, flood protection and cultural heritage. Given that flood protection and cultural heritage of waterways are included in other Melbourne Water strategies, and our limited role regarding recreation, it was decided that amenity should be the sole social value to be included in the HWS. 38 Healthy Waterways Strategy 2013/ /18 Chapter 3: Key values our waterways support

5 Amenity is also enhanced by the work of others in: > Providing facilities such as seats, shelters, paths or jetties > Landscaping of open space > Providing continuous public space and access along waterways > Managing recreational use and conflicts e.g. dog walkers and bike riders, rowers and powerboat users > Providing controls on adjacent development that may impose on the waterway landscape or change the sense of place. While Melbourne Water can work with others to influence these aspects to a greater or lesser extent, our key responsibility is to manage the waterway as a setting that provides amenity to the community. See Chapter 4.2: Advocacy for additional information on Melbourne Water s role in advocating for amenity outcomes. In the Healthy Waterways Strategy, amenity condition is assessed using Melbourne Water s biennial Community Perceptions survey results. This telephone survey is designed to provide a picture of community expectations and level of satisfaction with waterways. Priority areas were identified using the action response conceptual models (see Figure 3.1: Amenity conceptual model), an assessment of proximity, visitation and ability to traverse along waterways, and community input on important areas of value. For more information on the assessment of amenity condition, see the Healthy Waterways Strategy Resource Document. Conceptual model amenity at waterways INFLUENCES AND CONFIDENCE AROUND INCREASING satisfaction with amenity NATURAL PHYSICAL FORM Waterways with a more natural physical form (including the shape of the banks, the meander pattern of the waterway) and no concrete in the channel will increase satisfaction with amenity. VEGETATION Abundant and healthy looking vegetation that supports animals and birds is the most important factor in increasing satisfaction with amenity. The exact type of vegetation that improves amenity differs for individual locations and needs to be understood at each location. Indigenous vegetation is preferable as this has benefits for other values also. WATER QUALITY This aspect of waterways detracts from the naturalness. Water that is clear of oils, colours, litter and smells will increase the satisfaction with amenity. ACTIONS and advocacy ACTIONS and advocacy LITTER No or little litter in or around the waterway will increase satisfaction with amenity. This is based on the relationship between presence of litter and satisfaction with waterways. Melbourne Water Primary Responsibility. Melbourne Water has high influence through onground actions and advocacy Melbourne Water and others share responsibility. Melbourne Water has medium influence through onground actions and advocacy Others primary responsibility. Melbourne Water has low influence through advocacy. ACTIONS and advocacy SATISFACTION WITH AMENITY ACTIONS and advocacy ACTIONS and advocacy advocacy SENSORY ACCESS Clear sensory access to the waterway will increase satisfaction with amenity. This relates to the sense of naturalness at the waterway including aspects such as a waterway corridor free from obtrusive development and the ability to see and hear water or birds. FACILITIES Availability of well-maintained facilities (chairs, benches, tables, toilets, bbqs, bins) for general use will increase satisfaction with amenity. Note the facilities must not detract from the naturalness of the place. Proximity of paths and access along waterways. The type of facilities expected at different locations will vary. Figure 3.1: Amenity conceptual model: Actions and influences to protect and improve amenity 39

6 3.3 Birds Birds are one of our most visible, studied and monitored classes of animal, and their presence has a positive influence on how people feel about the health of waterways. Many birds have become specialised to certain wetland habitats or depend on regular access to water for many life processes such as feeding or breeding. Crakes, rails and bitterns (marsh birds) generally rely on dense vegetation found around wetlands and waterways for cover and protection during breeding, moulting and daily foraging. Some birds, such as the black-winged stilt, rely on variations in natural water depths and flows to trigger breeding. Many wetlands and waterways are popular spots for birds and birdwatchers. Data have been collected from 11,000 bird surveys at wetlands or along waterways in the Port Phillip and Westernport region. Most of these come from voluntary bird surveys compiled by BirdLife Australia. Native water-dependent bird species are considered in two sub-sets: streamside and wetland birds. Some 57 wetland bird species and 113 streamside bird species are expected, having been regularly found at water habitats and occurring widely within the Port Phillip and Westernport catchments. The assessment examines bird communities in an area, rather than looking at only one or a few selected species. The assessment considers measures of: > Species richness the number of expected bird species observed in an area (the number of different types of species recorded) > Frequency of occurrence of these species (the proportion of surveys in an area during which each species was recorded). This analysis has been used to help identify priority areas, develop the action response conceptual model (see Figure 3.2: Bird conceptual model) and develop an understanding of expected outcomes for target setting. For more information on the assessment of bird condition, see the Healthy Waterways Strategy Resource Document Condition assessments. Changes in waterways can have significant impacts on the behaviours and threaten the health of bird populations. The bird conceptual model expresses the types of management actions that can protect and improve conditions for birds. BIRDS SUPPORTS Riverine Quality and Connectivity Floodplain Quality and Connectivity Protect/Improve CONFIDENCE IN RESPONSE TO ACTION Improve conditions and structure of vegetated streamside areas Establish appropriate environmental flow regimes Improve water quality Control introduced predators (i.e. foxes, cats, dogs) in streamside areas Control weeds to improve the proportion of native vegetation Create more floodplain based wetlands Control introduced predators in wetlands areas Improve conditions and structure of vegetated wetlands (stormwater) Improve condition and structure of vegetation between wetlands Improve water quality in floodplain wetlands by managing inputs Figure 3.2: Bird conceptual model: Actions and influences to improve conditions 40 Healthy Waterways Strategy 2013/ /18 Chapter 3: Key values our waterways support

7 CASE STUDY Adaptive management at the Western Treatment Plant Melbourne Water manages the Western Treatment Plant (WTP), near Werribee, where it treats 54% of Melbourne s industrial and domestic wastewater. However, the WTP is also listed as a wetland of international importance under the Ramsar convention and is a popular birdwatching site some say second only to Kakadu for birdwatching in Australia with more than 280 species recorded. These include several threatened species and other species that migrate between their northern breeding grounds and Victoria; a round trip of about 30,000km each year. As site manager, Melbourne Water is responsible for conservation as well as wastewater treatment. In 2002, to meet Victorian Government requirements to reduce the adverse environmental effects of excess nitrogen discharge from the treatment plant on Port Phillip Bay, Melbourne Water instigated an Environment Improvement Plan that led to major treatment upgrades that improved effluent quality and reduced the treatment area at WTP. However, investigation and modelling predicted significant nitrogen reduction would adversely affect important protected species such as filter-feeding waterfowl. To comply with federal legislation (Environment Protection and Biodiversity Conservation Act) and protect important species and habitat, Melbourne Water developed a Ramsar and Conservation Management Plan and EPBC Strategic Compliance Plan for WTP. Under these plans, Melbourne Water aimed to ensure that any adverse impacts to bird communities would be addressed by implementing an adaptive management approach involving on-ground mitigation works, research, monitoring and annual reporting. This allowed us to learn from management decisions and apply new knowledge. An example of this approach was our response to declining waterfowl populations at WTP between 2004 and WTP employees modified their on-ground actions, from water flow manipulation to nutrient supply, based on the latest information about the impacts of the drought, and associated predictions of impacts on bird population to identify management changes. The region supports several other Ramsar-listed areas the Edithvale-Seaford Wetlands and Western Port. These are home for significant bird species such as the nationally endangered Australasian bittern and migratory birds. Waterbirds at rest 41

8 3.4 Fish Waterways contain an interesting and diverse variety of fish, with 36 species of freshwater fish (native and introduced) found in rivers, lakes and wetlands and a greater number in estuaries. Due to declines in abundance, several of these species are of national conservation significance (such as dwarf galaxias and Australian grayling). Fish also play an important role as a recreational value, with the Macquarie perch, Murray cod and river blackfish highly valued by the fishing community. Fish play an important role in waterways; they are usually near the top of the aquatic food chain and also provide food for people and some birds. Fish depend on rivers, estuaries and wetlands in several ways. They rely on variations in natural water flows, including flooding, to trigger breeding, spawning and migration. A large number of species, such as Australian grayling and short-finned eel, need to be able to move between the ocean and freshwater habitats to perform critical stages of their life cycle, such as breeding. The structure of waterways is also vital to fish because they need deep pools for resting, undercut banks and logs to hide under and streamside vegetation as an important food source. In the Healthy Waterways Strategy, fish condition is assessed by examining freshwater fish populations rather than single species and using measures of: > Species richness the number of types of species comparing the numbers of fish species recorded against the fish species expected > Nativeness the proportion of species that is native. This analysis has been used to help identify priority areas, develop the action response conceptual model (see Figure 3.3: Fish conceptual model) and understand the expected outcomes for target setting. For more information on the assessment of fish condition, see the Healthy Waterways Strategy Resource Document Condition assessments. Changes in waterways can have significant impacts on the behaviours and threaten the health of fish populations. The fish conceptual model expresses the types of management actions that can protect and improve waterway condition to best support fish. CASE STUDY Research into an effective environmental flow regime for Australian grayling Australian grayling are a fish species protected under the federal Environment Protection and Biodiversity Conservation Act 1999 that rely on flow cues to trigger spawning and migration. They occur in several areas in the Port Phillip and Westernport region including the Tarago River. It is widely recognised that high flows in autumn trigger adult grayling to spawn and larvae to drift down to the estuary and the sea where juveniles spend four to six months before another high flow in spring/summer triggers their upstream migration. Scientists use records of natural streamflows in a particular system to recommend volume, timing and duration for such triggering events, and Melbourne Water has worked with researchers to undertake monitoring to quantify the link between flow and grayling migration. Acoustic tracking and monitoring of adult grayling have shown the movement of individuals has a significant link to increases in streamflow, also coinciding with spawning. The next piece of the puzzle is to confirm that the migration of juveniles into the freshwater reaches is also linked to high flows. The research will use techniques that allow the daily ages of fish to be determined and provide information on the habitat occupied by a fish at any time throughout its life. When combined, these methods allow retrospective determination of the date on which a juvenile fish left the marine environment and entered freshwater. This research will allow the timing of migration to be pinpointed and compared to streamflows observed in the river at that time. The learnings from this research will ensure that delivery of environmental water to the Tarago River is efficient and effective in achieving the objectives of maintaining self-sustaining populations of Australian grayling. Australian Grayling (photo courtesy of Tarmo A. Raadik/DSE) 42 Healthy Waterways Strategy 2013/ /18 Chapter 3: Key values our waterways support

9 FISH SUPPORTS Riverine Quality and Connectivity Floodplain Quality and Connectivity Protect/Improve Improve habitat quality by revegetation of degraded rural streamside areas maintain existing areas of habitat within waterway channels in rural areas CONFIDENCE IN RESPONSE TO ACTION Implement appropriate environmental flow regimes Reduce competition and predation by introduced fish species Provide fish passage at barriers Improve streamside habitat quality in small streams through tree weed control (especially willows) and vegetation management Reintroduce large wood debris into the river system maintain or reduce DCI to <5% or <1% through water sensitive urban design Improve urban water quality through stormwater treatment in existing and new developments Improve habitat quality by revegetation of degraded urban streamside areas Improve streamside habitat quality through groundcover and shrub weed control maintain existing areas of habitat within waterway channels in urban areas Improve streamside habitat quality in large streams through tree weed control (especially willows) and revegetation Create more refuges within floodplains for wetland species Figure 3.3: Fish conceptual model: Actions and influences to improve conditions Rock work for fish passage at Tarago River, Robin Hood Reserve 43

10 3.5 Frogs Frogs can be found at many locations within the Port Phillip and Westernport region and are an integral part of waterway ecology. Some species commonly heard are southern brown tree frogs, spotted marsh frogs and the common froglet. Frogs are amphibians, which means they spend a portion of their lives entirely in water as well as on land. Most frogs undergo metamorphosis from a juvenile water-breathing form the tadpole to an adult air-breathing form. As such, frogs depend on wetlands for certain critical stages of their life cycle. In addition to metamorphosis, most species of frog breed and lay eggs in or around wetlands. The southern brown tree frog is a common species in greater Melbourne and may be found in suburban gardens. Wetlands are important for the laying of eggs and the development of tadpoles. In contrast, the Victorian smooth froglet lays its eggs on land in moist fallen leaves or in vegetation in areas that will later be flooded, and so rely on the floodplain connection between waterways and land for their survival. Water quality is also important to the development and survival of frogs. Their skin is very sensitive and able to absorb water from waterways and the atmosphere, so poor water quality is detrimental to them. Frogs are recognised throughout the world as environmental indicators due to this sensitivity to pollutants in the water and air. Frogs are usually very difficult to find and identification often occurs by recording their calls. Some 18 species of frogs have been found in the rivers, lakes and wetlands in the Port Phillip and Westernport catchments. Frog condition is assessed by the diversity of frog species, or species richness, found in an area rather than considering only one or a few species and comparing this to the number of species expected to have occurred there historically. This analysis has been used to help identify priority areas, develop the action response conceptual model (see Figure 3.4: Frog conceptual model) and the understanding of expected outcomes for target setting. For more information on the assessment of frog condition, see the Healthy Waterways Strategy Resource Document Condition assessment. Changes in waterways can have significant impacts on the behaviours and threaten the health of frog populations. The frog conceptual model expresses the types of management actions that can be undertaken to protect and improve conditions for frogs. FROGS SUPPORTS Riverine Quality and Connectivity Floodplain Quality and Connectivity CONFIDENCE IN RESPONSE TO ACTION Treat urban stormwater before entering waterways Improve condition and structure of vegetated streamside and wetland areas Control introduced predators (i.e. foxes, cats, dogs) Control weeds to improve the proportion of native vegetation Protect/Improve Build new wetlands close to existing waterways Reduce abundance of introduced fish Improve condition and structure of vegetated streamside and wetland areas Create connecting vegetation corridors to link breeding habitat Provide underpasses on roads to reduce human disturbance Treat agricultural runoff before entering wetlands/ waterways Treat urban stormwater before entering waterways Figure 3.4: Frog conceptual model: Actions and influences to improve conditions 44 Healthy Waterways Strategy 2013/ /18 Chapter 3: Key values our waterways support

11 CASE STUDY Melbourne Water Frog Census Frogs are important indicators of waterway health and can be found in wetlands and creeks and even suburban gardens. Frogs are difficult to see but can be readily identified by their calls. The Melbourne Water Frog Census is a community-based biological monitoring program that teaches the community to recognise frog calls in order to identify them. The Frog Census provides valuable data on the location and type of frog species while contributing to the responsible management of frog populations in Melbourne and raising awareness of waterway health. Information from the Frog Census is collated to form an overall picture of the distribution of various frog species around Melbourne. More than 70 people contributed recordings of frog calls, 165 sites were monitored and 13 species of frogs were recorded. The endangered growling grass frog was recorded 13 times; in contrast, the common froglet was recorded 130 times. Growling Grass Frog 45

12 3.6 Macroinvertebrates Dragonflies, beetles and freshwater crayfish are among a diverse group of animals called macroinvertebrates. These are animals without a backbone that live or spend some of their lifecycle (eggs, larval stage) in waterways. Most freshwater macroinvertebrates can be seen with the naked eye, and are generally smaller than 30mm. There are thousands of macroinvertebrate species and many types of worms, snails, mites and fly larvae belong to this group. Macroinvertebrates are a food source for platypus, fish and frogs. They are very sensitive to changes in the environment. Results of macroinvertebrate community analysis allow assessment of the impact on waterways, including their in-stream habitat (such as submerged logs in pools, rocks in small rapids, and vegetation on the banks), flows and pollution. The Healthy Waterways Strategy uses SIGNAL scores (Stream Invertebrate Grade Number Average Level) to assess the condition of macroinvertebrates. SIGNAL is a biotic index that uses the differences in the sensitivity of stream invertebrates to water and habitat quality to calculate a score to indicate the state of waterways. Some macroinvertebrates are more sensitive to environmental changes than others and, if a waterway is degraded, tolerant groups will be found more frequently than sensitive groups. Along with the development of the action response conceptual model (Refer to Figure 3.5: Macroinvertebrate conceptual model), the application of SIGNAL scores has been used to help identify priority areas, and increase the understanding of expected outcomes for target setting. For more information on the assessment of macroinvertebrates condition, refer to the Healthy Waterways Strategy Resource Document Condition assessments. Changes in waterways can have significant impacts on the behaviours and threaten the health of macroinvertebrates. The macroinvertebrate conceptual model expresses the types of management actions that can be undertaken to protect and improve conditions for macroinvertebrates. Dytiscid beetle (photo courtesy of Edward Tsyrlin and John Gooderham) 46 Healthy Waterways Strategy 2013/ /18 Chapter 3: Key values our waterways support

13 Macroinvertebrates SUPPORTS Riverine Quality and Connectivity Floodplain Quality and Connectivity Protect/Improve Improve condition and structure of vegetated streamside and wetland areas in rural areas Reintroduce large wood into peri-urban and rural waterways CONFIDENCE IN RESPONSE TO ACTION maintain and improve habitat in waterway channels through stabilisation works in rural areas Treat urban stormwater before entering rural waterways Treat agricultural runoff before entering waterways Improve condition and structure of vegetated streamside and wetland areas in peri-urban areas Improve condition and structure of vegetated streamside and wetland areas in small streams maintain and improve habitat in waterway channels through stabilisation work in peri-urban areas Establish appropriate environmental flow regimes Treat urban stormwater before entering peri-urban waterways Improve condition and structure of vegetated streamside and wetland areas in urban areas maintain and improve habitat in waterway channels through stabilisation works in urban areas Improve groundcover and shrub condition in vegetated streamside, urban and wetland areas Treat urban stormwater before entering waterways in urban areas Reintroduce large wood into urban waterways Improve water quality in floodplain wetlands through sediment and stormwater treatment Build wetlands Figure 3.5: Macroinvertebrates conceptual model: Actions and influences to improve conditions 47

14 3.7 Platypus The platypus is an unusual animal that is unique to Australia. It is a predator that relies on aquatic invertebrates for food. Feeding occurs only when the platypus is in water, and the platypus depends on water for survival. A decline in platypus numbers has been recorded since 1996 throughout waterways in greater Melbourne, primarily thought to be a result of the drought and increasing urbanisation. There has been an improvement in platypus numbers in some areas since the extensive flooding in 2011, however several platypus populations across the region are considered to be small and isolated and therefore at significant risk of extinction. In the Healthy Waterways Strategy, the condition of platypus populations is assessed by examining the relative abundance (catch per unit effort) of the populations. This method has been used to help identify priority areas, develop the action response conceptual models (see Figure 3.6: Platypus conceptual model) and the understanding of expected outcomes for target setting. For more information on the assessment of platypus condition, see the Healthy Waterways Strategy Resource Document Condition assessments. Photo: Courtesy of cesar 48 Healthy Waterways Strategy 2013/ /18 Chapter 3: Key values our waterways support

15 Platypus SUPPORTS Riverine Quality and Connectivity Floodplain Quality and Connectivity Protect/Improve CONFIDENCE IN RESPONSE TO ACTION Improve condition and structure of vegetated streamside and wetland areas maintain and improve channel habitat through stabilisation work and prevention of stock access Establish appropriate environmental flow regimes minimise litter in waterways Connect fragmented platypus populations Control introduced predators (i.e. foxes, cats, dogs) Weed control to improve nativeness of vegetation Treat urban stormwater before entering waterways Treat agricultural runoff before entering waterways Build wetlands Create refuges within floodplains Figure 3.6: Platypus conceptual model: Actions and influences to improve conditions 3.8 Vegetation Vegetation is the general term used to describe a group of plants in any one place. Vegetation is vital to the health and function of waterways within the waterbody (in-stream vegetation) and alongside it (riverine and floodplain vegetation). The type and structure of vegetation is important for providing food, shelter and habitat for animals, improving soil and water quality, providing stream bank structural stability, and providing shade and temperature control within waterways. In the Healthy Waterways Strategy, vegetation condition is assessed using the Index of Stream Condition (ISC) streamside zone score. The ISC combines information on the width, continuity and diversity of native vegetation, with information on weed cover to evaluate the overall health and quantity of streamside vegetation by comparing it with an Ecological Vegetation Class (EVC) benchmark. In Victoria, plants are grouped into EVCs based on their types and structure. An EVC consists of one or a number of plant species that are associated with a recognisable environmental niche (such as an estuary), and that can be characterised by several adaptive responses to ecological processes. The Department of Environment and Primary Industries (DEPI) has defined all EVCs within Victoria. The ISC was correlated with a more spatially detailed rating of vegetation quality undertaken for the development of the Healthy Waterways Visions, which will communicate Melbourne Water s medium-term aims for the form and function of waterways in the Port Phillip and Westernport region (see Chapter 7). The correlated data was used to identify priority areas, and to understand expected outcomes for target setting. For more information on the assessment of vegetation condition, see the Healthy Waterways Strategy Resource Document Condition assessments. A limitation of the assessment process is the focus on the immediate streamside zone, which does not adequately assess floodplain wetland vegetation that occurs some distance from the waterway channel. Throughout the life of the HWS, Melbourne Water will work to increase understanding of the condition of vegetation within these areas. The following conceptual model (Figure 3.7: Vegetation conceptual model) expresses the types of management actions that can protect and improve riverine vegetation and floodplain vegetation. 49

16 vegetation SUPPORTS Riverine Quality and Connectivity Both Riverine and Floodplain Quality and Connectivity Floodplain Quality and Connectivity Protect/Improve CONFIDENCE IN RESPONSE TO ACTION maintain and improve vegetation condition and structure within waterway channels Improve condition and structure of vegetated streamside and wetland areas Weed control to improve the proportion of native vegetation Exclude stock from streamside and wetland areas Control introduced herbivores (rabbits, goats, deer) Reduce vegetation clearance Establish appropriate environmental flow regimes Improve condition and structure of vegetated streamside and wetland areas Figure 3.7: Vegetation conceptual model: Actions and influences to improve conditions 50 Healthy Waterways Strategy 2013/ /18 Chapter 3: Key values our waterways support