To compensate for a paltry amount of winter run-off, Sask Water has decided to divert water flowing out of Lake Diefenbaker into Last Mountain Lake throughout the summer.

Last Mountain Lake is expected to be in "the lower half of its range" during the summer months, meaning water levels will hover at 489 metres, said Bart Oegema, senior hydrologist for the Crown corporation. At this level, some boaters in the north end of the lake will have problems launching their craft, he added.

Sask Water hopes to solve such problems by increasing the lake's elevation by about one metre. For this to happen, a greater volume of water from the Qu'Appelle system must pass through the Craven Dam.

The diversion from Lake Diefenbaker only began in recent weeks because ice cover on the Qu'Appelle River inhibited water flows between the two lakes, said Oegema.

Ice cover on the Qu'Appelle did not, however, stop Sask Water from diverting flows from Wascana Creek into Last Mountain Lake over the course of the winter.

That decision was met with some controversy at the legislature in recent weeks because water flows from Wascana Creek -- which feeds into the Qu'Appelle system -- contain treated effluent from the City of Regina's tertiary plant.

Concerns were raised by cottage owners and residents over the water's quality. But Alex Banga, director of basin operations with Sask Water, has said the effluent is "highly treated" and forms a small amount of the current flows now entering Last Mountain Lake.

"Right now, there's a flow of about 10 cubic metres per second going past Lumsden, and about six through Craven," he said of the recently redirected water flows into Last Mountain Lake. "But out of that, only a fraction is coming from the treatment plant."

When the Wascana Creek and Qu'Appelle River join over the winter, flows vary from one to 1.2 cubic metres per second.

"Of that, we put 80 per cent ... into Last Mountain Lake," said Oegema. "This is not common, but it has happened in at least four other years since 1984 during drought years."

Saskatchewan Environment officials said the winter diversion took place at the request of cottage owners and residents on the lake.

But Greg Brkich, water critic, recently said in the legislature that Last Mountain Lake communities would not have agreed to receiving any water that originated from the Regina plant.

While the winter diversion "helped somewhat" to improve water levels, it was still not enough to meet Sask Water's target, said Oegema. Round Lake, Crooked Lake, Echo Lake and Pasqua Lake are also below target levels and will also receive diverted water from Lake Diefenbaker throughout the same period.

Public concerns over Last Mountain Lake's water quality will be up for town hall discussion at the Regina Beach Memorial Hall at 7:30 p.m. on May 27. Mayors from Regina Beach and Buena Vista, as well as Larry Spencer, MP for Regina-Lumsden-Lake Centre, will attend.