The water at Edmonton's popular accidental beach has "failed to meet water quality standards," according to the North Saskatchewan Riverkeeper.

Testing at the new beach in Cloverdale on Tuesday showed 238 colony-forming units (CFU) of E. coli per 100 millilitres of water, earning the popular recreation spot a "red" rating from the Riverkeeper group in its latest water-quality update.

Three other beaches — at Laurier Park, Capilano Park and the Fort Edmonton footbridge — all earned green ratings for water quality this week. Results were posted to the Riverkeeper website Friday afternoon.

This Riverkeeper tracks water test results on its website. (Riverkeeper) For a beach to earn a "green" rating, E. coli levels must be at or below 200 CFU/100 ml.

The testing showed the accidental beach didn't meet Health Canada guidelines for recreational water quality, said Hans Asfeldt, manager of water literacy with the North Saskatchewan Riverkeeper and Swim Drink Fish Canada.

"This isn't something to be frightened about," Asfeldt said. "It's a very small exceedance — just over 200 [CFU/100 ml], which is the guideline federally.

"It's not a matter of the water being safe if it's within the guideline and unsafe if it is above. It's much more the case that there are risk levels to consider regardless of how much bacteria are in the water."

For beaches that fall within the guidelines, Health Canada expects that one or two out every 100 swimmers will contract a water-borne illness such as diarrhea or vomiting, Asfeldt said. When E. coli levels are higher, the risk of getting sick increases.

'Water quality changes quickly'

But people should note that ratings only reflect the water quality at the time of sampling, he said.

"The water quality changes quite quickly, given that the beach is on a river, and moving water. So the results from Tuesday really are a reference point. The water is going to be distinct from that — today, tomorrow, any time this weekend."

The Riverkeeper's recreational water monitoring program conducts tests along the river at key access points within the city of Edmonton. Results are accessible on its website and through the Swim Guide app.

Asfeldt said when water levels in the river are particularly low, water quality may be poorer because any discharges into the river are more concentrated.

"Ultimately, if you want the cleanest water, choose a location that's more upriver. Further upriver you go, the cleaner it's going to be. Again, it's really a matter of what level of risk you're willing to tolerate, not only in terms of water quality but also in terms of the physical risks that are inherent to swimming in a moving body of water."

He said the accidental beach may be affected by Mill Creek, which is "notorious for discharging a fairly significant load of contaminants into the river" just upstream of Cloverdale.

"It's possible that some of that discharge from Mill Creek sort of hugs the south bank of the river, around the bend, right into Cloverdale.

"But again, from day to day and even hour to hour, water quality can change and we shouldn't write off Cloverdale as a poor-quality beach just based on one day's results. Because certainly there will be days when other locations are worse, just depending on the conditions."