The Maribyrnong River remains under heavy stress with new data revealing only 2 per cent of the catchment meets Victorian water quality standards.
An online report card released by the state government last week showed densely populated urban and industrial sites and the lower Maribyrnong River are under severe stress (2 per cent of the catchment) and medium density urban and suburban sites are under considerable stress (12 per cent).
Water quality in the remaining 84 per cent, mostly in the upper and mid-catchment, was considered ‘fair’ with some evidence of stress caused by agricultural runoff.
The Cleaner Yarra River and Port Phillip Bay Report Card found natural geology and heavy stormwater had eroded significant areas of streamside habitat.
“The highly urbanised regions of the catchment rated ‘poor’ and ‘very poor’ due to significant impact from these pressures,” the report found.
“Waterways such as Steele Creek, Stony Creek and Maribyrnong River at Canning Street in the lower reaches of the catchment typically have higher nutrient and metal concentrations that are introduced through stormwater.”
Water quality was tested at 16 sites from July 2012 to June 2013, measuring nutrients, water clarity, oxygen, salinity, acidity and metals.
Environment Minister Ryan Smith said the online report card provides comprehensive water quality information for the community.
“The health of Maribyrnong catchment continues to improve,” he said.
“Understandably, and consistent with waterways around the world, as the Maribyrnong draws closer to urban areas the water quality becomes poorer.”
He said evidence showed the river nevertheless supported a rich diversity of native plants and animals, with platypus numbers at their highest in at least five years.
