Climate change could put Lake Diefenbaker water quality at risk

Despite a high concentration of nutrients, Lake Diefenbaker's water quality has been rated moderate — at least for now.

Study shows cloudy water saving reservoir from algae blooms

Researchers say the water quality of Lake Diefenbaker is moderate, but lower flows from the South Saskatchewan River could make things worse. (Submitted by Lorne)

Despite a high concentration of nutrients, Lake Diefenbaker's water quality has been rated moderate — at least for now.

Complaints from local people about an increase in algae blooms spurred the University of Saskatchewan's Global Institute for Water Security to do a major study of the lake's water quality.

The study found a high percentage of phosphorus in the water, a nutrient that could create large amounts of algae.

"It could be at a tipping point," said research associate Rebecca North. "It seems like the moderate water quality is being maintained now, but any additional inputs of nutrients to the reservoir could result in declines of water quality."

It seems like the lake's cloudy water is saving the reservoir so far. Algae needs sunlight, as well as nutrients, to grow.

If the amount of water coming in from the South Saskatchewan River declines, the water could become clearer, exposing the nutrients to sunlight.

"The flow coming in from the South Saskatchewan River originates from snow melt and precipitation patterns in the Rocky Mountains," she said. "Any kind of change in those precipitation patterns or snow melt will cause algal blooms. Climate change estimates predict we will have reduced flows in the future."

Algae can be a serious problem for people who use drinking water from lakes.

"Under certain conditions, they can produce algal toxins," she said. "The city of Toledo, last summer, had to close down their drinking water supply because of algal blooms in Lake Erie."

North said there are things that local landowners can do to reduce the amount of nutrient flowing into the water through runoff.

"I would say that we can do some land management practices along the South Saskatchewan River to increase the particulate loading flowing into the reservoir to keep it turbid," she said. "The turbidity is what keeps it from blooming."

Researchers from the University of Saskatchewan tested the water at Lake Diefenbaker over a span of three years. They combined their research with historical research done by the University of Regina to see if the water quality was declining.


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