The Minnesota Pollution Control Agency (MPCA) is seeking comments on a water quality improvement report for Little Rock Creek in Morrison and Benton counties. The report, known as a Total Maximum Daily Load (TMDL), focuses on pollution that has caused low dissolved oxygen, high nitrate levels, and elevated water temperatures. A public comment period begins Feb. 4 and continues through March 6.
Little Rock Creek is a designated trout stream and drinking water source that begins in Morrison County and flows through Little Rock Lake near Rice, before eventually entering the Mississippi River. The creek was originally placed on the MPCA’s impaired waters list in 2002. The dissolved oxygen, nitrate, and temperature issues were discovered since then and added to the impairment list in 2010. High nitrate levels were also discovered in Bunker Hill Creek, a tributary to Little Rock Creek, and added to the 2010 list as part of this project.
The report indicates that a 52 percent reduction in total oxygen demand, a 29 to 47percent nitrate reduction, and 1 percent thermal loading reduction is needed for Little Rock Creek to meet water quality standards.
The TMDL report is part of a nationwide effort under the federal Clean Water Act to identify and clean up pollution in streams, rivers and lakes. Every two years, states are required to submit a list of impaired waters to the U.S. Environmental Protection Agency (EPA). A TMDL report is a scientific study that calculates the maximum amount of a pollutant a water body can receive (known as the “loading capacity”) without exceeding water quality standards.
After receiving public comments, the MPCA will revise the draft Little Rock Creek TMDL report and submit it to the EPA for approval. Following EPA approval of the study, a plan will be developed to reduce pollution throughout the watershed.
The Little Rock Creek TMDL draft report is available on the MPCA’s TMDL projects webpage, or at the agency’s St. Paul office, at 520 Lafayette Road N.