The Minnesota Pollution Control Agency recently released a five-year report on the state’s nutrient reduction strategy (NRS).
NRS outlines how Minnesota will reduce nutrient pollution in its lakes and streams and reduce the impact downstream. The strategy specifies goals and provides a framework for reducing phosphorus and nitrogen levels.
The NRS, adopted by 11 organizations in 2014, calls for reducing nutrient levels by 10% to 20% over much of the state by 2025, with much larger long-term reductions by 2040.
The NRS calls for a progress report every five years to evaluate whether Minnesota is on track for reducing nutrient pollution. In looking at data from intensive river monitoring efforts across Minnesota over the past 10 and 20 years, MPCA officials say there is both good and bad news to report.
The good? Phosphorus concentrations, the amount of phosphorus per liter of water, have generally decreased.
The bad? Nitrogen concentrations have increased at many locations.
For both, high year-to-year variability makes it difficult to detect trends at many of the monitoring locations.
Over the last decade, MPCA says in 24 of 50 (48%) river sites, phosphorus showed decreasing trends, with all other sites showing no detected trend. For nitrate-nitrogen, the dominant form of nitrogen in polluted rivers, 14 of 38 sites (37%) had increases, with the rest having no detected trend.
Over the past 20 years, similar patterns were found. The Mississippi River monitoring sites near the Twin Cities showed phosphorus concentration decreases of 21% to 26%. Whereas nitrate had 20-year increases in the range of 25 to 34%. Further downstream closer to the Iowa border, the Mississippi River phosphorus concentrations have dropped by 50% and nitrate was too variable to detect the trend.
In the Red River of the North, phosphorus concentrations over the past two decades have decreased in the upstream reaches but increased at the Minnesota-Canada border. With some exceptions, river nitrate concentrations increased in the Red River Basin.
Future plans, monitoring
In order to make the wide-scale changes to significantly reduce nutrient pollution, MPCA maintains that Minnesota needs large-scale collaboration at all levels and in all sectors of industry/municipal and agriculture. Over the next five years, MPCA says state partner agencies and organizations will need to identify and address barriers impeding the scaling-up of new BMP adoption. Specific to ag, strengthening Minnesota’s soil-health building emphasis and new private-public partnerships for 4R nutrient stewardship will be important, the agency says.
Feedlot inspections showed a high rate of compliance — about 97% — related to runoff at the feedlot facility itself. However, inspections of land application of manure showed considerable room for improvement concerning setbacks from waters, rates of nitrogen applied, record-keeping practices, and soil phosphorus testing and management, MPCA says.
Read the full report online.