State of the Environment Report 2007
In WA the term 'wetland' is commonly used to refer to a standing water body or inundated land, and 'waterway' is commonly used to describe a water body flowing in a channel. Wetlands may include lakes, swamps, damplands, sumplands, springs, soaks, karst caves and waterholes. International and national definitions of wetlands are much broader and include waterways and near-shore marine areas (see below). While the exact number of wetlands is not known, there are thousands of wetlands in WA and they range from permanent, to seasonal or intermittently inundated systems.
Wetlands are widely recognised as important wildlife habitats and as being the most biologically productive and diverse ecosystems. They directly and indirectly provide a broad range of ecosystem services, and support of a wide variety of flora and fauna. Some wetlands are of international significance, particularly as habitat for migratory bird species. Wetlands serve to purify water by removing suspended matter, biologically processing contaminants and removing plant growth nutrients. They also provide flood control by storing and retaining stormwater and runoff. Many wetlands also provide considerable enjoyment for the people of WA through recreation, tourism, landscape amenity, and for cultural and historical reasons.
In the past little regard has been given to the value of wetlands, with many people viewing these water bodies as swamps (and refuges for disease) best converted into land suitable for farming, housing or roads. This perception is now changing and wetlands are becoming more valued by the community. Despite this, wetlands in WA continue to be lost (from impacts such as filling, draining and land development) or severely degraded (though impacts such as land clearing, excessive fire, grazing, altered water regimes, salinisation and acidification).
The Ramsar Convention on Wetlands of International Importance (held in Iran in 1971), to which Australia and 99 other nations are signatories, defines wetlands as 'areas of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water the depth of which at low tide does not exceed six metres'. The State Wetland Conservation Policy (Government of Western Australia, 1997) accepts this definition, but separates the conservation and management of WA's rivers, estuaries and shallow marine areas due to special attributes and values of those environments. This State of the Environment Report also reflects the State policy direction, separating marine waters and flowing waterways from the above wetland definition.
The Wetlands Conservation Policy for Western Australia (Government of Western Australia, 1997) outlines objectives relevant to the conservation of wetlands. Specifically:
Very little information is currently available about the spatial extent of WA wetlands and even less on their condition. No systematic survey of wetlands or wetland values across the State has yet been conducted, although a number of coordinated wetland mapping and classification projects have been undertaken or are underway. The State's largest and most prominent wetlands (usually large lakes) are well documented. Western Australian wetlands listed for recognition under the Convention of Wetlands 1971 (also known as the Ramsar Convention) include the Ord River floodplain; lakes Argyle, Kununurra, Forrestdale, Thomsons,
Gore and Toolibin; the Peel-Yalgorup, Vasse-Wonnerup, Lake Warden and Muir-Byenup systems; and the Becher Point wetlands. Other important wetlands (including waterways and near shore marine areas) that are nationally important have been documented in A Directory of Important Wetlands, Third Edition (Environment Australia, 2001).
Most available information pertains to wetlands on the Swan Coastal Plain, which is defined as the coastal strip of land west of the Darling Scarp, north of Dunsborough and south of Jurien. This is the most populated region in WA and is under significant urban development and growth pressures. Although difficult to ascertain, previous estimates indicate that 70-80% of original wetlands on the plain have been cleared, drained or filled since European settlement (Balla, 1994), although with continued wetland losses this figure is likely to be much higher. The ecological function of many remaining wetlands has been so significantly altered that they now bear little resemblance to their original state (Environmental Protection Authority, 2004). In 2004 approximately 36% of the Swan Coastal Plain was wetlands, by area. Of the remaining wetlands, about 17% have high conservation significance and only 14% are protected through formal statutory policies such as environmental protection policies (Figure IW3.1).
A review of the Swan Coastal Plain Wetlands Environmental Protection Policy indicates that many valuable wetlands are still in decline. Between 1996 and 2004, Land Monitor showed that 4% of vegetation in remaining wetlands was lost or became severely degraded (Figure IW3.2). This represents an approximate rate of loss of 1500 ha (equivalent to about 750 football ovals) of wetland area each year. About 6% of wetlands lost or degraded during this time were of high conservation significance (Figure IW3.2, Table IW3.1).
![Figure IW3.2: Percentage of wetland loss or degradation on the Swan Coastal Plain by local government area, 1996-2004. [Data source: Department of Environment - geomorphic wetlands [ver. 2005], Department of Land Information - Land Monitor [ver. 2004], EPP Lakes Policy [ver. 1992]; Analysis: EPA; Presentation: EPA.]](/site/files/images/Figure-IW3.2_Large.jpg)
Many wetlands of South West WA have been extensively cleared, especially in the Wheatbelt, and those remaining are under significant pressure. Limited but intensive monitoring of 25 regionally important wetlands indicates that 26% are deteriorating, with rapidly declining biodiversity (Cale, Halse & Walker, 2004). Long-term monitoring of about 40 wetlands in the conservation estate shows 12% were impacted by rising salinity between 1977 and 2000 (Lane et al., 2004). Other wetlands outside the conservation estate are likely to be significantly more degraded by dryland salinisation. Given that over 90% of land in the Avon River catchment has been cleared, many remaining Wheatbelt wetlands do not reflect their pre-European settlement condition.
Very little is known about wetlands in the rangelands and the arid interior. Further research is required to determine their condition.
Wetlands on the Swan and Scott coastal plains of South West WA are being lost or degraded at an alarming rate by altered catchment water balances, drainage, development, salinity, acidity, pollutant discharge, dieback, weed encroachment and insensitive fire management. Climate change is also an ominous threat for remaining wetlands, particularly in the South West, where a drying climate is expected. The most extensive impacts have occurred in urban areas where wetlands have been excluded from conservation by poor town planning, excessive clearing has been allowed, or there has been inadequate buffer distances, poor drainage planning or stormwater management. Remaining wetlands in major urban and regional centres undergoing growth are facing significant developmental pressures due to increasing land values and the need to enhance supporting infrastructure (e.g. roads, railways, pipelines). Many wetlands are also being lost or degraded because landowners are generally unaware that wetlands include seasonally waterlogged and inundated areas as well as water bodies permanently filled with water. For example, a World Wildlife Fund (WWF) study of metropolitan Perth landholders with conservation category wetlands on their property reported that 70% of landholders were unaware of the presence of a wetland, let alone a conservation category wetland, on their property (C Mykytiuk, WWF, pers. comm.).
Wetlands are also being degraded through poor water quality and loss of vegetation (see 'Loss or degradation of native vegetation'). Widespread catchment clearing and subsequent altered water regimes can pose an inundation threat to wetlands (see 'Altered water regimes'). Over-abstraction and excessive drainage of groundwater may also lead to some wetlands drying out and becoming subject to acidification (see 'Acidification of inland waters'). Excessive erosion of soils and leaching of nutrients from household gardens and agricultural land may lead to sedimentation and eutrophication in wetlands (see 'Eutrophication' and 'Erosion and sedimentation'). Livestock that access wetland areas can damage vegetation, soil and water quality, leading to enhanced erosion and sedimentation problems (see 'Loss of fringing and instream vegetation'). Saline and acidic waters are also entering and degrading many Wheatbelt wetlands (see 'Acidification of inland waters', 'Salinisation of inland waters'). Contamination and fires are also impacting some wetlands (see 'Land contamination' and 'Altered fire regimes').
Environmental protection policies: Two environmental protection policies (EPPs) have been developed by the EPA to protect wetlands in WA. A South West Agricultural Zone Wetlands EPP was established in 1998 to protect and enable rehabilitation of Wheatbelt wetlands. Placement of wetlands on the register is voluntary and so far only two wetlands are listed as protected wetlands under this policy. The Swan Coastal Plain Lakes EPP was established in 1992 to protect several hundred lakes. It was recently revised by the EPA with the option of extending protection to other wetland types, however the State Government decided not to implement a revised version of the EPP.
Planning policy: A Water Resources Statement of Planning Policy (Western Australian Planning Commission, 2006a) has been developed by the Western Australian Planning Commission to assist with the management and protection of wetlands (and other waterways) in the land use planning system. An accompanying draft Guideline for the Determination of Wetland Buffer Requirements (Western Australian Planning Commission, 2005) has also been released to provide advice on minimising planning and development impacts on wetlands.
Vegetation clearing regulations: In 2003 amendments were made to the Environmental Protection Act 1986 to provide for regulations that afford increased protection for native vegetation, including that associated with wetlands.
Wetlands conservation policy: was established in 1997 with a statement of policy outlining key objectives including prevention of further loss or degradation of valuable wetlands, and promoting wetland conservation, creation and restoration (Government of Western Australia, 1997). The Wetlands Coordinating Committee was formed to oversee the policy's implementation and is currently reviewing and finalising an updated version of the policy.
Wetland protection and conservation: The Department of Environment and Conservation has a lead role in protecting and managing wetlands, including most of WA's nationally and internationally important wetlands. The Department has a lead role in the development of a framework to outline a statewide process for the mapping, classification and evaluation of wetlands. A wetland restoration and management manual is being developed to provide an understanding of how wetlands function, causes and effects of degrading processes, restoration and management techniques, and planning and legal aspects. Programs affiliated with other organisations such as Landcare, Wetland Watch or Land for Wildlife also enhance the conservation and management of wetlands through private land and pastoral lease agreements.
Wetlands education and incentives: Technical and financial support for wetland protection is available to farmers and private landholders through programs funded by the Natural Heritage Trust and the National Action Plan for Salinity and Water Quality, the Department of Environment and Conservation's Healthy Wetland Habitats program and WWF's Wetland Watch program. Centres dedicated to wetland conservation have been established in Cockburn (Bibra Lake), Melville (Piney Lakes) and Capel. These aim to promote wetland values, conservation and sustainable ecosystem management through education and public awareness. A collaboration between universities and the State Government has resulted in the WA Wetlands Database which provides cumulative information about WA wetlands.
Management groups: Traditional owners have Native Title representative bodies that help facilitate an important cultural and legal bridge between traditional obligations to look after wetlands and contemporary management. Regional natural resource management groups are also working to map, restore, rehabilitate and prevent further degradation of wetlands. Currently, the Swan, Northern Agricultural and South Coast regional groups are undertaking wetland mapping projects.
Loss of wetlands can reduce the capacity of the land to mitigate floodwaters or stormwaters, by acting as water storage points in the landscape and reducing the speed at which water moves across the land. When wetlands are cleared and filled for development, this may contribute to rising water tables and early onset of flooding, waterlogging and salinisation in susceptible areas, requiring construction of extensive and costly drainage networks in an attempt to remove excess water from the landscape. Wetlands are highly productive ecosystems providing a range of important ecosystem services. Though wetlands are most often associated with waterbirds, they provide essential habitat for a wide variety of species of birds, mammals, reptiles, amphibians, fish and insects, and are especially important as drought refuges in summer. With the current extent of wetland loss in some parts of WA, many remaining wetland flora and fauna are now rare, threatened or endangered. Loss of wetlands also removes the opportunity for enjoyment of their natural beauty, recreational and tourism opportunities, and cultural and spiritual values.
4.10 Develop and implement a strategy that protects Swan Coastal Plain wetlands using a combination of incentives and existing conservation and regulatory protection mechanisms.
4.11 Review the Environmental Protection (South West Agricultural Zone Wetlands) Policy.
4.12 Finalise and implement the revised Wetland Conservation Policy for Western Australia.
4.13 Implement the Water Resource Statement of Planning Policy and finalise the draft Guideline for the Determination of Wetland Buffer Requirements.
See also 'Loss or degradation of native vegetation'.
