Lake study needs dry year data

High water levels in Saskatchewan’s Lake Diefenbaker make it difficult to study algae blooms and water quality problems

Years of higher than normal precipitation and spring runoff have left researchers studying the long-term health of Lake Diefenbaker short on dry weather data.

“Our study was mostly conducted during wet years and so we didn’t find any evidence of real widespread algae blooms or anything,” said Rebecca North, research associate with the Global Institute for Water Security at the University of Saskatchewan.

“We do hypothesize that when the flow is reduced, so under low flow conditions, there will be increases in algae blooms and declines in water quality.”

The GIWS has been involved in a study along with other U of S departments, and the University of Regina on the health of Lake Diefenbaker.

“There hadn’t been any kind of long-term studies on the whole of the reservoir, particularly special patterns, so seeing if things where the river came in were different from near the dams where it was more functioning like a lake,” North said.

GIWS’s research was completed from 2011 to 2013 — their findings were recently published in a special issue of the Journal of Great Lakes Research.

The group collected water samples year round and looked at the amounts of phosphorus and nitrogen in the water. From those samples they found that the water quality depends mostly on what comes down the South Saskatchewan River.

Jeff Hudson, biology professor at the U of S, has also been involved in the studies. His group has completed studies from 2011 to 2014 — they have had to scale back their studies this year due to insufficient funds.

“The type of work we do is looking at the nutrients in the water column and we’ve been looking at also the algae and a variety of other physical, chemical parameters in the water column,” Hudson said.

Hudson’s group has found that the extreme water flows have created a lot of turbidity in the lake water.

“If we continue with these extreme weather events, which include high precipitation events in the foothills of the Rocky Mountains, we may see high flows and lots of turbidity and nutrients entering the reservoir,” Hudson said.

Hudson said that they now have a good portion of the behaviour of the reservoir understood but they still want to get a handle of what happens with it during dry periods.

Both North and Hudson are hoping for funding to continue to continue studying the lake during dry years.


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