MANKATO — “Of course the (river) flow goes up when it rains more. Precipitation has gone up about 8 percent since 1940. Has flow gone up proportionally with that? No, it’s gone up more than that.” And Schottler said climatology records show precipitation has not increased in May and June in southern Minnesota, months that river levels are often highest.
Schottler said erosion of riverbanks and widening of the channel are natural occurrences on any river, but it’s been greatly accelerated on the Minnesota. And while much of the sediment that erodes into rivers under normal conditions settles somewhere in the same river, sediment in the Minnesota is flowing out into the Mississippi at a higher rate.
“If you go to non-ag watersheds, there is still erosion but no increase in sediment leaving the river.”
Fisher worries that limited funding to help improve the river may be targeted to a tiny portion of the problem.
There are two things involved in looking at suspended solids in the river: the physical sediment (dirt) and the biological. The biological side includes things such as algae blooms created by excess phosphorus in the river.
Much of the focus has been on reducing phosphorus, which comes from fertilizers and city wastewater treatment plants. With treatment plants having been upgraded all along the river — including in Mankato and St. Peter — that source of phosphorus has been significantly reduced.
Still, Fisher said, much of the funding is being aimed at further improving Twin Cities metro area wastewater treatment and storm water storage.
“ The MPCA studies are calling for 1 percent of the problem to be fixed in the metro area for $850 million.
I struggle with spending that to fix 1 percent of the problem,” Fisher said.
“I understand they want everyone to do their part.
Politically, (farm) producers say urban areas need to do their part. I understand that.”