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New PDT segments on impaired waters list

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The Pomme de Terre River has new entries on the state's list of polluted lakes and streams.

The 2008 Total Maximum Daily Load List of Minnesota's polluted lakes and stream segments has been finalized.

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After undergoing extensive public review, the list was approved last week by the U.S. Environmental Protection Agency. The list, which is updated every two years, has 1,475 impairments on 336 rivers and 510 lakes. There are 150 new listings for river reaches and 147 new listings for lakes.

Two segments of the Pomme de Terre were on previous lists, for fecal coliform and turbidity. However, new segments of the river have been added to the 2008 list and include pollutants such as mercury in fish tissue.

The section of the Pomme de Terre River on the impaired waters list are Muddy Creek to Marsh Lake, Pelican Creek to Pomme de Terre Lake, Stalker Lake to Tenmile Lake, and Tenmile Lake to Pelican Creek.

The TMDL List submitted to the EPA identifies all the impaired water bodies for which a TMDL study is required. The TMDL List is a subset of the overall Inventory of Impaired Waters, which includes waters that need a TMDL plan as noted above and those for which plans have already been developed and approved by the EPA.

The inventory also includes water bodies that are naturally impaired, such as the arsenic exceedances in the Red River of the North. The total number of impairments on the inventory is 2,575.

Only a small fraction of Minnesota's lakes and streams have been assessed so far for impairments. About 40 percent of the waters the Minnesota Pollution Control Agency has monitored and assessed do not meet water-quality standards.

Shannon Lotthammer, who oversees water-quality monitoring for the MPCA, said an increase in the number of known impaired waters does not necessarily mean that Minnesota's lakes and streams are becoming more polluted. "Increased monitoring makes us aware of the impairments," Lotthammer said. "Once we have water-quality data, we can work with our partners to clean up waters that are impaired, and we can better protect water bodies that are not impaired."

The MPCA is working with partners across the state to address impaired waters. Approximately 100 water-quality-improvement studies are being conducted on about 420 water bodies. Additionally, the EPA has approved 16 water-quality studies that address 99 impairments. Those waters are now in the restoration phase of the process.

The listed waters contain pollutants at levels above acceptable limits to protect the public for specific uses, such as fishing or swimming. For each impairment, the Clean Water Act requires that a TMDL study be prepared. The study results in a calculation of the maximum amount of a pollutant the water body can receive and still meet water-quality standards. It also allocates needed pollutant reductions among all the point and nonpoint sources. Once water-quality standards are being met, the water is removed from the impaired waters list.

The 2008 Impaired Waters list, methodology for listing and regional maps are available on the MPCA's Web site at www.pca.state.mn.us/water/tmdl/tmdl-303dlist.html.

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