SHAKOPEE, Minn. - The Minnesota River is getting healthier, and the Minnesota Pollution Control Agency (MPCA) says it shows efforts to reduce pollution from wastewater treatment systems are making the difference.
MPCA staff monitored a 20-mile stretch of the lower river for three weeks in August to see if the hot, dry summer and low flows would deplete oxygen levels, which had been a problem in previous droughts.
Scientists were encouraged to find that oxygen levels remained high enough to support fish, bugs and other aquatic life despite the stressful conditions.
"It's often difficult to show environmental gains because it can take decades to show significant progress. Therefore, when we have achievements, we need to celebrate them," MPCA Commissioner John Linc Stine said. "This happy discovery really emphasizes that environmental advances are long term and the resources dedicated are worth it.".
Officials credit the success to about $250 million in public and private investments to reduce phosphorous discharges all along the river.
"Over the past several years, wastewater treatment plants along the affected stretch of the river implemented several phosphorus-reduction strategies that are working based on the good dissolved oxygen levels we found in this survey," said Glenn Skuta, MPCA water monitoring manager. "There were no violations of the dissolved oxygen water quality standard."
Some of these phosphorus-reducing strategies include:
- stabilization ponds avoiding discharge from June through September,
- upgraded wastewater treatment for 12 communities with inadequate sewage treatment, and
- Improved phosphorus removal in wastewater treatment that surpassed permitted goals for wastewater phosphorus loading to the basin ahead of schedule.
The permit also established a phosphorus trading program to allow new and existing permitted facilities flexibility in how they comply with wastewater effluent limits.
The Minnesota River has consistently been named as one of the state's most endangered waterways, and has made national lists of the most polluted rivers and lakes.
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