Scientists with the Minnesota Pollution Control Agency are taking water samples from the Minnesota River Friday to see if there's enough oxygen in the river to support aquatic life.
They're taking a boat down a 22-mile stretch of the river, from Jordan to where the Minnesota meets the Mississippi.
The MPCA's Glenn Skuta says the hot, dry summer has contributed to a slower flow and warm waters that are typically followed by low oxygen levels.
Skuta says that could trigger a fish kill, and that's a concern for a fishery that has rebounded in recent years.
"There's a great improvement in the number of anglers fishing on the Minnesota River over the last decade and such," he said. "So we want to make sure when we hit these rare events like this one -- where we get down to a flow that we haven't seen since 1988 -- that we are protecting the river at that kind of a critical condition."
Skuta adds that climate change may make this summer's scenario more common in the future.
"The likelihood of seeing drought or low-flow conditions like we're seeing now may very well increase as time goes on," he said.
Low dissolved oxygen comes from phosphorus that enters the water. The test samples should help scientists determine if tougher standards on water-treatment plants are working.
If they're not, Skuta says the MPCA will have to look at what else can be done to control phosphorus in the river.