Testing of water in Calgary's Bow River has found high levels of the deadliest form of E. coli after flooding hit the city two weeks ago.

CBC News paid for analysis of river water to see how it has been affected by the catastrophic flooding that hit the area this year, sending huge volumes of sewage and runoff into the river.

Chris Bolton, the CEO of Benchmark Labs in Calgary, said he found high levels of E. coli O157 — the deadliest strain of the bacteria — in water tested on June 27.

The sample, which was collected from the Bow River next to the Bonnybrook outfall pipe, also exceeded the guidelines for nitrate, dissolved solids and turbidity.

The Bonnybrook treatment plant continues to operate at just two-thirds capacity since the flooding.

While water treatment plants will ensure drinking water downstream stays safe, Bolton says anyone using the river for recreation, irrigation or fishing should be aware how easily they could get sick.

"If you have a dog, for example, that goes to swim to catch the ball that comes back, that's soaking wet, your young child pets the dog, puts the hand to the mouth and it happens to collect E. coli, obviously that's a situation you wish to avoid," he said.

Alberta Environment is monitoring the quality of both drinking water and river water, but says it has no concerns.

Less recreation

Government spokeswoman Renee Hackney said farmers aren't using river water for irrigation and most people are still avoiding the Bow River altogether.

"The high flow actually assists in lowering risks, as people are typically not recreating in them," she said.

But according to Bolton, with E. coli present in the rivers at rates as high as 150,000 colony forming units (CFU) per litre, the water is very unsafe.

"That's at least 800 times the acceptable level for recreational use," he said.

"Their response of 'don't worry and no one will use the river' is inappropriate."

Bolton says the province should be looking for the source of the pathogen.

The Elbow River results showed higher values for contaminants in the sample collected in Calgary, but most parameters remain within the guidelines.

According to the results, E. coli levels exceed the guidelines in both samples. 

Benchmark used the Guidelines for Canadian Drinking Water Quality prepared by the Federal-Provincial-Territorial Committee on Drinking Water for comparison.

Testing sites

View E. coli in Calgary rivers testing sites in a larger map
With files from CBC's Scott Dippel