Stinky Sturgeon river caused by decaying plants as water level stays high

Officials say June's record rainfall is causing a bad smell at the Sturgeon River. CTV News Edmonton's Evan Kenny explains why.

The sulfurous smell of the Sturgeon River isn’t an abnormal occurrence, though it tends to be an odorous problem earlier in the season.

During winter, ice covers the river, lowering the oxygen level in the water, and vegetation starts to decompose, resulting in sulfur-containing compounds being produced.

• It’s not your imagination, the Sturgeon River does stink

It’s a common occurrence in all bodies of water in Alberta.

With the heavy rainfall the capital region has seen in June and July, the Sturgeon River has been elevated and vegetation that’s normally not underwater now is.

“This plant matter is decaying and using up oxygen in the water resulting in a sulphur-like smell,” the City of St. Albert wrote online.

“This odour will continue until the water recedes and the areas begin to dry out.”

Waterlogged and saturated soils also have low oxygen levels and will give off the same smell until dry.

The rainfall also had the potential to carry fertilizer from lawns into the river, which could increase the river’s metabolic rate, which could contribute to the smell, according to Rolf Vinebrooke, a professor of biological sciences at the University of Alberta.

“Another thing that’s happening, possibly, is because the Sturgeon River can be very productive with a fair amount of algae, and as the algae grow and then die off a little bit, they contribute to that dead organic material that can then suck up all the oxygen in the water, ” he added.

“For the rest of the summer, while the temperatures are gradually climbing and getting warmer and warmer, the same sort of processes that are sucking up the oxygen in the Sturgeon, it’s just going to (continue).”

The lower oxygen levels are also creating problems for fish, which are dying in certain areas of the river as they become trapped in warmer, shallow water.

The city reached out to the province for help and is working on removing fish carcasses and returning trapped live fish to the main channel of the river.

By Wednesday afternoon, the city had collected more than two dozen northern pike carcasses from the river, according to a government spokesperson.

Large amounts of fish carcasses can also create a particular odour, which is similar to the scent produced by blue-green algae.

“If the Sturgeon right now has lots of nutrients in it from the rainfall washout from all the surrounding residential areas, blue-green algae love that sort of pulse of nutrients,” said Vinebrooke.

“Certain types of blue-green algae can produce a chemical … and it’s got that sort of dead fish smell to it.”

With files from CTV News Edmonton’s Evan Kenney