MPCA outlines sediment reduction strategy for rivers

MANKATO – Long-term strategy for reducing sediment in the Minnesota River and Mississippi River south of the Minneapolis-St. Paul metro area were reviewed at a public meeting hosted by the Minnesota Pollution Control Agency (MPCA) Wednesday at the Blue Earth County Public Library.

The good news was that phosphorus levels in the waterways were reduced by 48 tons per year. The decrease was due largely to better wastewater treatment facilities, enabling levels to reach 2015 limits “five years early,” according to Larry Gunderson of the MPCA in St. Paul.

Despite significant efforts on measures to address water pollution affecting the Minnesota River, the current rate of progress is not resulting in sediment reductions needed to meet other water quality standards, according to the MPCA. Because most of the South Metro Mississippi River suspended sediment load comes from the Minnesota River, river basin efforts directly affect downstream areas.

Data recorded from 2008 to 2011 showed Minnesota River Total Suspended Solids (TSS) was measured at 7 percent at Lac Qui Parle Dam (northwest of Montevideo), 26 percent at Morton, 35 percent at Judson, 97 percent at St. Peter and Jordan, 100 percent on the Mississippi River at Red Wing and 50 percent at Winona, according to the MPCA.

Gunderson said higher TSS levels between Morgan and Jordan and at Red Wing are caused by high-loading tributaries including the Blue Earth River, and the metro area. Other sediment sources listed were ravines, riverbanks, bluffs and upland watershed erosion.

Sediment Reduction Strategy ranges from traditional conservation practices that reduce soil erosion from cropland to innovative practices and programs that increase land water storage, according to the MPCA.

Sediment Reduction Strategy emphasizes the importance of civic engagement in the process of setting short and long-term goals, tracking progress, and providing adaptive management for future research and monitoring.

Excess sediment sources in the Minnesota River Basin and its tributaries come from a variety of sources, according to the MPCA. They are grouped into four broad categories: uplands (surface erosion from fields, urban areas and other land uses); ravines and gullies; bluffs; and stream banks.

Erosion from fields and urban areas are referred to as “upland sources;” ravines and bluffs, and steam banks are referred to a “near-channel sources: and are currently believed to be the greatest contributors to increased Minnesota River Basin sediment, according to the MPCA.

Proposed interim targets are a 25 percent reduction by 2020 and 50 percent reduction by 2030. Eventually, an 80-90 percent reduction from current sediment loading is needed to meet the Minnesota River Sediment TMDL (Total Maximum Daily Load).

Significant changes in policy, technology and science are expected over the next 25 years. A full report is available on the sediment reduction strategy web page: www.pca.state.mn.us/ark8qrf.

A public comment period on Minnesota’s draft Sediment Reduction Policy continues through April 17. Submit comments to Gunderson in writing or e-mail at Larry.gunderson@state.mn.us. His address is Minnesota Pollution Control Agency, 520 Lafayette Road, North; St. Paul, MN 55155.

(Fritz Busch can be e-mailed at fbusch@nujournal.com).

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