FORMER policeman, Murray-Wellington Liberal MLA Murray Cowper has accused the Department of Water (DoW) of "stealing" water off farmers and other property owners along the North Dandalup River.
By "turning off" the water, the DoW has contravened an agreement, signed when the North Dandalup Dam was built, to provide environmental flows sufficient to meet riparian water rights of downstream property owners, Mr Cowper and the North Dandalup River Landholder Group claimed.
The dam is on the escarpment above the town, which is named after the river 70 kilometres south of Perth.
Last Friday it was at 58 per cent capacity, holding 35.25 gigalitres as part of Perth's Integrated Water Supply Scheme (IWSS).
Since December 29 it has held more than 35gl for the first time, with a record 36.28gl set on February 24, according to Water Corporation figures.
Below the dam, the North Dandalup River which meanders across the coastal plain to Peel Inlet, is a series of stagnant waterholes.
Landowners claim "old timers" who farmed the region before them, recalled that prior to the dam the river flowed all year, fed by a spring now behind the dam wall.
The only time in living memory it stopped was for about a week during a major bushfire in the early 1960s, they said.
Some six kilometres north, Dirk Brook which also rises above the escarpment and flows into Peel Inlet, but is not dammed, was a flowing stream, landowners pointed out.
"What they (DoW) have done is tantamount to stealing water in my view," Mr Cowper said last week.
"They made a commitment and they are now depriving lawful use of that water, in my view that's stealing.
"An agreement signed when the dam was opened in 1994 provided for regular releases of water to sustain the river environment and also to adequately provide for the riparian water rights of a dozen or so downstream farmers.
"The agreement provided for releases to cease at the beginning of winter after opening falls of 60mm or more of rainfall, however an on-site ranger liaised with landowners to ensure their needs were met.
"All of this clicked in after 61mm of rain was recorded back in April, but water management procedures at North Dandalup dam have changed, the on-site ranger can no longer sanction water releases when they are necessary, and there has been no rain since."
Mr Cowper said DoW's refusal to restore environmental flows in the absence of more rain had led to needless stress for landowners and the environment.
He called on Water Resources Minister Mia Davies to make good, promises to maintain a flow of water.
"The locals want to hear from the minister, they are sick of the absolute bureaucratic nonsense they get in department responses," he said.
"It (North Dandanlup Dam) has been receiving winter top ups from both the Stirling dam at Harvey and from the Binningup desalination plant to ensure adequate drinking water for Perth - 60 per cent of all Perth's drinking water comes from my area.
"But they lose 27gl of it through leaking pipes.
"They are trying to save some of the water they lose to leaks in Perth by taking it off the farmers down here."
Acting Water Resources Minister Terry Redman confirmed last week he would not ask the DoW to "change their current practices" which he said were "based on scientific and environmental assessment".
Mr Redman said Bureau of Meteorology data showed rainfall in the South West so far this year was about 16pc below the long-term average and scientific research indicated up to a 50pc reduction in run-off into rivers and streams.
Water releases from IWSS dams, including North Dandalup, had been "significantly reduced" in recent years to "maximise storage for high-value public water and scheme supply under the drying trend," he said.
Mr Redman said this change was outlined by the DoW in 2010.
"We are in a drying climate and downstream users should start planning to move to alternative sources such as groundwater or, where available, scheme supply, given the long-term drying trend which is predicted," he said.
Mr Redman said the change had already resulted in several landowners applying for licences to take groundwater and reduce reliance on river water.
A communications process between DoW and downstream landowner representative Bruce Campbell was established in 2012 with meetings at the start of each water release season and were on-going if there were changes to release volumes or landholder concerns about flow rates, he said.
In response to landowners' concerns and lower than anticipated rainfall, an extra 17.5ml was released from North Dandalup Dam on May 12-19, Mr Redman said.
He said storage volumes in North Dandalup were often higher than natural inflow because the Water Corporation used it to store water from other sources for the IWSS.
Mr Redman said Ms Davies' office had offered Mr Cowper a full briefing on this issue on June 8 but he had declined.