When are effluent nutrient limits excessive?

The City of Moorhead, Minn., takes issue with phosphorus regulations designed to protect a lake in Canada

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In Wisconsin, where I live, there has been some controversy about phosphorus in wastewater discharges: Will P removal simply cost too much, especially for small communities? Accordingly, Wisconsin developed an adaptive approach so that instead of (or in addition to) changing its process to remove phosphorus, a plant could work with landowners on the receiving water to reduce P inputs from runoff.

Now there’s another phosphorus controversy brewing in a neighboring state. Minnesota Public Radio (MPR) and other news organizations are reporting that the City of Moorhead opposes a new state rule designed to help reduce P inputs to Lake Winnipeg, north of the border in Canada. Under the rule, Moorhead’s 4.5 mgd (average) treatment plant would have to cut P levels in its discharges to the Red River, which ultimately feeds the lake. The aim is to help prevent summer algae blooms.

“The Moorhead plant is a small part of a big problem,” MPR reports. “On average it emits 132 pounds of phosphorus each day, but that is less than half of one percent of the phosphorus flowing into Lake Winnipeg. The Minnesota Pollution Control Agency wants Moorhead and 13 other wastewater facilities to reduce phosphorus output,” in Moorhead’s case by about 100 pounds per day. That would mean process changes costing some $10 million. 

Meanwhile, neighboring North Dakota, with which Minnesota competes for jobs and economic development, does not impose P limits.

In this case there’s also the issue of whether Minnesota clean-water agencies should have to make costly treatment changes for the benefit of a water body in another country. In other localities it’s simply a question of whether it makes sense to force treatment plants to curtail P when the vast majority of it comes from other sources, mainly runoff from agricultural land. 

What’s the situation with phosphorus limits in your state or community? Do you face limits for which compliance will be costly? Do you feel such limits are justified on environmental grounds? I would welcome your thoughts on any issue related to phosphorus discharges and permit limits. Send me an e-mail to editor@tpomag.com and I promise to respond.

Read more about Moorhead’s situation at http://minnesota.publicradio.org/display/web/2013/02/05/environment/moorhead-fights-against-pollution-regulations



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