The West –
Almost 200,000 homes with backyard bores face tougher rules on their use as water levels in the Gnangara aquifer system — Perth’s most important drinking water supply — hit new lows.
Citing declining rain, the Department of Water and Environment Regulation flagged “reductions over time across all water users” of the Gnangara system.
The changes are likely to cut entitlements for thousands of businesses but the department yesterday confirmed residential bore owners could be affected.
The metropolitan area has about 177,000 backyard bores, taking about 88 billion litres a year.
Residential bores are not licensed or metered, prompting the department to suggest it may have to resort to other ways of cutting their use.
This could include changes to sprinkler rosters which bans bore use during winter but allows them to be used three days a week for the rest of the year compared with only two days for scheme supplies.
Other measures included encouraging alternative supplies such as recycling.
Department director-general Mike Rowe said even though bores took pressure off the Water Corporation, reducing their effect on the Gnangara system was prudent.
“Our research shows us there is plenty of room for improvement in the way garden bores are used, and that generally domestic garden bore users use more water for the same type and area of garden than scheme water users,” Mr Rowe said.
A report by the department paints a bleak picture of the Gnangara system, where almost two-thirds of sites used to monitor its health are in breach of ministerial conditions.
Of the 30 monitoring sites, 18 had water levels below those deemed acceptable during 2015-16, an increase from 16 the previous year.
Mr Rowe told a Budget estimates hearing there was a need to “rebalance” the use of the Gnangara system, and a new allocation plan would involve across-the-board cuts.
“It will involve groundwater reductions over time across all water users, including water utilities, local government and other people who rely on groundwater, such as horticulturalists and others,” he said.