Perry Lakes $2.6m water revival plan

By Lisa Calautti, 28 March, 2011

The Town of Cambridge has submitted the risk assessment report for its $2.6M Perry Lakes Aquifer Replenishment Project to the WA Government.

The federally funded community infrastructure project to replenish Perry Lakes could raise the local water table by one and a half metres.

A significant decrease in winter rainfall over several years has caused Perry Lakes to dry out.

“This project is the first of its kind in Australia,” said Brett Jackson, Director of Projects at Town of Cambridge.

“It will be using treated waste water, so the Health Department needs to approve that safety standards are met,” Mr Jackson said.

“Town of Cambridge expects construction to start in September, with completion due by the end of December this year.

“After approval we can finish compiling the specifications, then tender for works,” he said.

The project, partnered between Cambridge, CSRIO and the Water Corporation, may eventually make more irrigation water available to local residents.

However, Mr Jackson said CSIRO’s scientific modelling process could not confirm this would occur.

Subiaco Wastewater Treatment Plant sends billions of litres of highly-treated waste water into the Indian Ocean each year.

The aquifer project will divert about two billion litres per year of the treated water to underground galleries dug near Perry Lakes.

Pumps will push this water through the galleries against existing groundwater, forcing a gradual rise in the water table.

Perry Lakes’ biodiversity of plants, birds and endangered Long-Necked Tortoises has struggled to survive with the scarcity of rain.

A bore currently pumps water into the east lake to keep it alive, while the west lake remains completely dry.

“Average rainfall figures show decreases of 10 to 15mm per decade over the last 40 years in Perth,” said Pat Ward, a meteorologist from the Bureau of Meteorology’s WA Climate Service Centre.

This significant decrease has created water shortages for the environment and human consumption in Perth.

“Trends show the Subtropical Ridge, which is a global high pressure band at southern WA’s latitude, is gaining strength,” said Mr Ward.

“This results in stronger high pressure systems deflecting cold fronts which may bear rain,” he said.

These cold fronts dissipate or slip further south, minimising rainfall over the southwest land mass.

Current trends and global climate model predictions suggest rainfall will probably keep decreasing in WA’s south, causing further drying of lakes.