The Auditor General of Western Australia (WA) released a report last month on the health of the Swan-Canning river system.
For those of you not lucky enough to have visited our fair city, the more casually known Swan River is an iconic watercourse of great natural beauty often associated with black swans, dolphins (sometimes sharks), boats and fireworks. In 2004 the WA Government even declared the Swan River as the State’s ‘first heritage icon’. Its Aboriginal Nyoongar name is the Derbarl Yerrigan and the Nyoongar people consider it to be formed by the Wagyl – a snakelike being from the Dreamtime that meandered over the land creating rivers and lakes.
The river begins as three major tributaries; the Avon River, Canning River and Helena River, eventually coming together to form the Swan River estuary which meanders its way out to the Indian Ocean at the port of Fremantle after a combined journey of ~280 km. The slow-moving river system drains a mighty catchment area of ~2,000 km2 of mostly agricultural and urban areas. The impacts of current and historical land uses have been felt by this river system over the last ~130 years however, and have made it vulnerable to a number of key environmental issues including nutrient loading, algal blooms, drainage from acid sulphate soils, fish kills, loss of habitat, invasive species, erosion due to boat wakes, and dredging.
In recognition of the need for a coordinated effort to look after this iconic river, the Swan River Trust was established in 1989 as a State government agency charged with protecting and managing the Swan Canning Riverpark, responsible to the Minister for the Environment. The Trust was initially constituted under the Swan River Trust Act 1988, which was replaced by the Swan and Canning Rivers Management Act 2006 and associated legislation in 2007. This Act requires the Trust to ‘protect and enhance the ecological and community benefits and amenity’ of the Riverpark and produce a River Protection Strategy to outline agency responsibilities for river management.
The Trust works with over 40 state and local government agencies that have management responsibilities for the waterways, public land and adjoining river reserves that make up the Swan Canning Riverpark. It has overseen a wide range of management projects to maintain and improve the health of the river system in its time, including revegetation and erosion management works, upgrades to oxygenation plants, drainage nutrient intervention works, and the installation of constructed wetlands. The most recent and impressive project currently underway is a constructed wetland located on the Ellen Brook tributary. It will be WA’s largest constructed wetland (at a cool $4 million), so positioned to reduce the nutrient load in the catchment currently contributing the highest levels of phosphorus and nitrogen into the Swan-Canning system. In addition, applications of a phosphorus-adsorbing slurry to the Ellen Brook were recently undertaken in efforts to reduce the nutrient loading from this part of the river system. In summary, an extensive amount of work has been done to maintain and protect the river – but has it been enough?
In this context, the objective of last month’s audit was to determine whether the environmental health of the Swan Canning river system is adequately protected. Understandably, issues such as these are sensitive and often prone to the politics of the times. In addition, agency responsibilities for river management are complex and often overlap.
However, the audit’s key findings were that:
- water quality in the middle and upper sections of the Swan Canning river system is in moderate to poor condition but declining, particularly as a result of nutrient influx relating to decades of human impact (rural and urban);
- a drying climate has meant less water flows into the river system and thus less nutrient run-off from agricultural areas. However, it has also meant less flushing in the upper rivers so that nutrient concentrations have remained high;
- the lower estuary is in reasonable health but seagrass and prawn populations have declined and salinity and water temperature have increased. The lower estuary is subject to similar pressures as the middle and upper sections but the effects are less obvious due to the larger body of water and regular flushing by tidal seawater.
As required under legislation, the Swan River Trust produced a River Protection Strategy (RPS) to establish goals and targets. It includes specific agency commitments for actions including the recommendation to monitor, evaluate, and report on the river systems’ health and success of actions undertaken to improve it. Unfortunately, seven years after the most recent legislation was passed, the Trust’s RPS has still not been approved. The amalgamation of the Swan River Trusts with the Department of Parks and Wildlife, which will require amendments to both the both the Conservation and Land Management Act 1984 and the Swan and Canning Rivers Management Act 2006, is unlikely to expedite the process.
While the Swan River Trust Board will remain as an advisory body to the Minister for Environment, there will no longer be an organisation which works directly to address the causes of the river system’s decline. Given the very large and complex task of dealing with the threats to the river’s health and responding to the Auditor General’s findings, an approved River Protection Strategy and targetted funding and staff need to be prioritised if we are truly interested in protecting the social, ecological and economic values of one of Perth’s most precious icons.