Minnesota debates phosphorus discharge limits for improved water quality

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Courtesy of Fluence Corporation

City leaders across the Minnesota River Basin are protesting proposed phosphorus standards, which they contend will be too expensive and have little or no effect on water quality.

In January, 41 of the 147 Minnesota cities in the basin outlined their objections in a letter to the governor and the Minnesota Pollution Control Agency.

Many of these cities’ wastewater treatment plants currently have phosphorus control technology in place, according to Daniel Marx, an associate attorney with the firm representing the Coalition of Greater Minnesota Cities and the Minnesota Environmental Science and Economic Review Board. Marx said the letter outlined specific technical and legal concerns regarding the proposed standards, and asked for meetings with the governor and the Minnesota Pollution Control Agency to discuss other solutions.

Marx added:

Many of these communities already are already meeting phosphorus standards of 1 mg/L or less in their wastewater discharges. […] The proposed regulations will be significantly more restrictive and require substantial upgrades. The proposed regulations won’t lead to attainment of the water quality standards and will have minimal impact on reducing algal growth in the river. […] Is this the best approach to helping the river? Modeling suggests it won’t have a significant impact.

Nutrient Pollution

The United States Environmental Protection Agency advocates the adoption of numeric water quality parameters for both nitrogen and phosphorus. It says these compounds are “the causal parameters directly responsible for eutrophication in immediate and/or downstream waters” and says having criteria will help states better protect waterways.

When fresh water is too rich with nutrients — called eutrophication — it becomes a breeding ground for algae. The nutrients include naturally occurring nitrates and phosphates, or those introduced by fertilizer runoff or sewage discharge. This can be resolved thorough better wastewater treatment, which reduces the amount of nutrients entering waterways, as well as stringent pollution controls.

Rhea Shu, president of the Natural Resources Defense Council, explained on AlterNet:

The immediate cause of the blooms can vary, but the common basics are these: Rains wash pollution from farms, septic tanks and other sources into our waters — from small streams and wetlands to great rivers and lakes — and municipal sewage systems add waste to these waters. These pollutants then supercharge the waters with nutrients like nitrogen and phosphorus. That feeds a population explosion for algae that feast on these nutrients. Warmer temperatures accelerate the growth.

The EPA says it considers nutrient pollution to be “one of America’s most widespread, costly and challenging environmental problems.”

Nitrogen and Phosphorus

Nitrogen and phosphorous are nutrients that enter the waterways through fertilizer or manure runoff. High levels can create conditions including harmful algal blooms, hypoxia, and high levels of nitrates in groundwater supplies.

To date, Hawaii is the only state to have in place a total numeric criteria for nitrogen and phosphorous for all waterways. The territories of American Samoa, the Commonwealth of Northern Marianas, and Guam also have these in place.

States with criteria for nitrogen and/or phosphorous for two or more water types include Minnesota, Wisconsin, New Jersey, and Florida. The U.S. Territory of Puerto Rico also has them in place.

Government officials from the Minnesota cities of Mankato and Glencoe say the new, more stringent phosphorus limits were not based on average flows, but rather on low river flows coupled with the highest discharge flows from treatment plants.

It could cost millions to add technologies to treatment plants to reach the lower levels — 1.5 mg/L in the case of the city of Glencoe.

The Minnesota River has been considered one of the state’s most polluted waterways. But in 2012, oxygen levels increased, which state pollution control officials attributed to “efforts to reduce pollution from wastewater treatment plants.” They also cited increased public and private investments in helping reduce phosphorus discharges.

Earlier Objections

This is not the first time city officials have objected to such oversights. A 2013 opinion piece in Treatment Plant Operator said there already had been some attempts by the state to place limits on plants discharging into Lake Winnipeg, which borders Canada. Part of that debate centered on whether facilities in the U.S. should be subjected to changes in water quality requirements for the benefit of another nation.

Opponents to the Minnesota phosphorous limits say they are not trying to eliminate regulations, but are seeking discussion with all stakeholders in the region in order to find a workable, cost-effective solution to the situation.

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