Protecting rivers from algae is the goal of water quality standards now being implemented by the Minnesota Pollution Control Agency (MPCA).
These standards – approved by the federal government – are designed to protect fishing and swimming from excess nutrients, particularly phosphorus. In excess amounts, phosphorus can cause algal blooms that turn waters green and slimy, and hurt fish and other aquatic life. Algae also make the water unsightly and smelly for swimming, paddling and fishing. Some forms can even make animals and people sick.
The new standards will allow the MPCA to identify waters where excess phosphorus is causing problems, and to develop strategies for reducing that phosphorus. One strategy involves requiring reductions in phosphorus in wastewater discharges.
Minnesota began addressing the problem of excess phosphorus in wastewater discharges the 1970s, with requirements to reduce phosphorus discharges to lakes. Since then significant progress has been made, but additional action is needed to protect Minnesota’s rivers and downstream waters, particularly in areas where phosphorus reduction is not currently required. The map below shows where action has already been taken, and where further reductions may be needed.
“These standards are the next step for Minnesota in protecting water quality. We know that nuisance algal blooms can have a detrimental effect on fish. Minnesotans may well remember the extensive fish kills in the Mississippi River and Lake Pepin in the late 1980s. We still have many rivers choked by algae in late summer,” said Katrina Kessler, water assessment section manager for the agency. “Working with wastewater facilities to reduce phosphorus discharged to rivers is one of the many steps we need to take to keep our waters fishable and swimmable.”
The agency will use a new custom approach to implementing the river standards. For each facility discharging to a river, the agency will examine the river’s health when that facility’s permit expires. Based on water monitoring data and other information, agency staff will determine if:
- Downstream rivers meet standards and no stricter limits are needed in order for the river’s health to be maintained
- Downstream rivers meet standards but the facility discharge has potential to trigger algal blooms and thus needs stricter limits
- Downstream rivers fail to meet standards and already grow nuisance algae, meaning the facility needs to further reduce phosphorus to help restore the water’s quality
Of the 714 municipal wastewater treatment facilities in Minnesota, 462 discharge to a river, 115 to a lake, and the rest to land.
The agency will consider all major sources of phosphorus in the watershed – the area draining to the river – when setting limits. This way, each facility will need to do its fair share and not more. However, this new approach is more complex and takes more time. The MPCA analyzes extensive data from many sources, including intensive water monitoring, stressor identification reports, drainage patterns, facility designs, river and discharge flows, computer simulations of water quality changes, and much more.
For some communities, these standards will not change anything. For other communities, the standards may result in to the need to upgrade their wastewater treatment.
Because upgrades can be costly, the MPCA is working closely with communities to develop approaches and timelines for meeting the standards. Gov. Mark Dayton included $167 million in additional funding for water infrastructure, including wastewater treatment upgrades, in his bonding bill for the 2016 legislative session.
The agency worked on the standards for several years. The rule-making process included significant public comment, a formal public hearing and a legal challenge. The MPCA Citizens Board (since disbanded by the Legislature) approved the standards and the Minnesota courts upheld them.
These standards are part of Minnesota’s efforts to reduce phosphorus pollution. Statewide, municipal wastewater phosphorus discharges have decreased by 70% over the past 15 years.
Nationally, the U.S. Environmental Protection Agency has asked all states to develop standards for phosphorus to protect aquatic life. One side benefit to Minnesota’s standards is that they will help the state meet its responsibilities to reduce the phosphorus that reaches the Gulf of Mexico and causes hypoxia.
For more information:
- Phosphorus in wastewater: https://www.pca.state.mn.us/water/phosphorus-wastewater
- Technical guidance on implementing river eutrophication standards: https://www.pca.state.mn.us/sites/default/files/wq-wwprm2-15.pdf
- Minnesota’s nutrient reduction strategy: https://www.pca.state.mn.us/water/nutrient-reduction-strategy