Contact: Cori Rude-Young, 651-757-2680
St. Paul, Minn. – President Reagan was in the White House and virtually no one had heard of the Internet the last time the Minnesota River was tested as it will be measured this week. What Minnesota Pollution Control Agency scientists and staff hope to find out is whether their standards for wastewater treatment along the polluted river are working.
This Friday MPCA water monitoring staff will launch boats in St. Paul and travel 20 miles on the Minnesota. Along the way they will grab water samples and place monitoring equipment that will stay in the river for a week. Staff will use the findings to see whether this hot, dry summer is causing low dissolved oxygen (“Low DO” for short) in this stretch of the river. Low DO causes multiple problems for aquatic life when the river is at low flow, including the potential for fish kills.
The testing should reveal the effectiveness of a 2004 MPCA plan that affected wastewater treatment plants along 22 miles of the Minnesota River. The Metropolitan Council and Xcel Energy will also take part in the effort by increasing their own river monitoring efforts during the survey.
If even lower flows develop, a similar follow-up survey will be performed in a few weeks to assess what is happening under even more stressful environmental conditions.
Dissolved oxygen – oxygen molecules dissolved in water – is a major indicator of water quality. Like the air we breathe, the survival of aquatic life depends on a sufficient level of oxygen dissolved in water. When it drops below levels necessary for sustaining aquatic life, it becomes a critical water quality impairment. Low DO comes from excessive algae growth, and subsequent death and decay, caused by phosphorus coming into the water. Sources of phosphorus include discharges from municipal and private wastewater treatment, cropland and urban stormwater runoff.
The 2004 Lower Minnesota River Low Dissolved Oxygen TMDL study made for tougher standards on wastewater treatment plants along the Minnesota River, forcing reductions in their phosphorus discharges by 40 percent. Wastewater treatment plants are already meeting their 2015 reduced phosphorus discharge goals, according to the MPCA researchers, but this low-flow condition is the first time they’ll be able to determine if these reductions are keeping the river’s oxygen levels healthy.
“It’s been 24 years since we’ve had a low-flow like this on the Lower Minnesota River,” MPCA Manager Glenn Skuta said, “so we need to do this monitoring now to see if all the good work done by wastewater treatment plants over the last decade has addressed the low dissolved oxygen problem. If not, we’ll need to look at what else can be done to control phosphorus in the Minnesota River Basin.”