Alberta researchers say gender-bending fish in the province's rivers are sending a concerning message about whether the water is safe to drink.
Two University of Calgary professors have been monitoring a small species of minnow in the Red Deer and Oldman rivers in the southern part of the province.
They found in some locations, females made up as much as 90 per cent of the population, far higher than the 55 to 60 per cent that is normally found.
At nearly every site studied, male fish also showed elevated levels of a protein that is normally only found in the blood of females.
The researchers found a large variety of chemicals that affect hormones in the water, both man-made and the result of agriculture.
Professor Lee Jackson says their study doesn't show whether the chemical levels are safe for humans to drink, but the findings are a concern and more research is needed.