Communities and industries continue to do their part to decrease phosphorus that causes algae in lakes and streams. Since 2000, Minnesota wastewater treatment facilities have decreased the amount of phosphorus in their discharges to surface waters by 71%, from 1,855 metric tons per year to 544 metric tons, according to the 2016 Pollution Report to the Legislature.
That sharp decrease stems from a strategy that the Minnesota Pollution Control Agency Citizens Board adopted in 2000 to address phosphorus limits in permits.
With the exception of nitrogen levels, which have remained relatively flat in wastewater discharges, facilities have also decreased the following:
- Total suspended solids which are sediment and other particles that cloud the water
- Mercury which is a toxic element that accumulates in fish tissue
- Carbonaceous biochemical oxygen demand which is a measurement of how pollutants can deplete oxygen needed by fish and other aquatic life
Facilities have managed to make this progress, even with growing populations and wastewater volumes, by investing in technology, equipment and training.
“State and local officials will need to continue their diligence to ensure that municipalities have effective treatment facilities and capacity for growth, to continue Minnesota’s legacy of wastewater operator excellence and water quality improvement,” the report states.
Wastewater permits are part of the MPCA’s water quality program designed to protect and improve the state’s rivers, lakes, wetlands and groundwater so that they support healthy aquatic communities and designated public uses such as fishing, swimming and drinking water.
Phosphorus loads discharged by Minnesota wastewater treatment facilities from 2000-2015