The Dawesville Channel was proposed as part of a broader management strategy to cap the phosphorous loading to the estuary and to make the system visibly clean and ecologically healthy.
While construction of the channel has to an extent alleviated the algal bloom and water-quality problems in the estuary, many of the symptoms of eutrophication are now seen in the lower reaches of the rivers which flow into the estuary.
Despite a widespread community effort to better manage the catchment area, phosphorous input into the catchment has remained static since construction of the channel and are well above levels set by the Environment Protection Authority.
In 2008, the Environment Protection Authority document titled Water quality improvement plan for the rivers and estuary of the Peel-Harvey system estimated that phosphorous discharge from the three river systems would need to be cut by almost 50 per cent.
While this plan identified farming practices as the major source of phosphorous, it also pointed to the growing contribution from urban populations as a significant contributing factor.
Urban development in the area has accelerated rapidly since the 1980s. The opening of the new Perth-Mandurah rail link and the building of the Perth-Bunbury Highway are expected to further exacerbate that growth.
In 2002, the Economic development and recreation management plan for the Peel waterways predicted that the population of the Peel Region would double to more than 110 000 people by 2021.
More people means more pressure on the natural systems and increased need to better manage these systems.
The plan concluded that;
...without corrective action, the Peel waterways will not be able to sustain the increased recreational demands of expected population growth. Under such stress, the environment will decline further unless resources are found for action in the catchment to improve water quality throughout the system, and affirmative action to restore the environment and habitats of the rivers, particularly the Murray and Serpentine.
There is an economic as well as an environmental motive for ensuring the continued health of our waterways.
The Peel Region's economy relies heavily on industries supported by the waterways - farming, fishing and tourism and recreation.
Efforts are well underway between catchment partners such as the Peel Waterways Centre, the Peel-Harvey Catchment Council and the South West Catchment Council, the Peel Development Commission and local government to ensure that future development is designed to have minimal impact on the natural environment.
Sources:
- Water Quality Improvement Plan for the Rivers and Estuary of the Peel-Harvey System", Environmental Protection Authority, 2007
- Economic Development and Recreation Plan for the Peel Waterways", Water and Rivers Commission, 2002
- Peel Geographic Perspective", Peel Development Commission/Peel-Harvey Catchment Council, 2003
- Securing the Future - Achievements of the Peel Inlet and Harvey Estuary Management Strategy 1989-1994", Waterways Commission, 1994
- State of Play - Peel-Harvey Eastern Estuary Catchment Environmental Assessment", Department of Water, 2007
- Peel-Harvey: The Decline and Rescue of an Ecosystem", Bradby, K, 1997
- Coastal Water Quality, Western Australia's Peel-Harvey Estuarine System", Australian Government, Department of Environment and Heritage, 2006
- Peel Inlet and Harvey Estuary Management Strategy; Report and Recommendations", WA Environment Protection Authority, 1985
- Ribbons of Blue" website, Waterwatch WA, 2008