Sediment reduction plan unveiled

The south metro Mississippi River is receiving nearly 1 million tons of sediment from other rivers annually, but a new cleanup plan has targeted the pollution sources and is calling for significant reductions.

The Minnesota Pollution Control Agency released the first draft of a TMDL — total maximum daily load — Wednesday that recommends the Minnesota River - the primary source of pollution to the south metro Mississippi reduce its sediment flow by up to 60 percent.

Other reductions stated in the TMDL include 50 percent from the Cannon River, 25 percent from urban runoff, 20 percent from the Upper Mississippi River and 20 percent from smaller rivers and streams in Minnesota and Wisconsin that flow directly into the Mississippi River.

The plan's goal is to reduce the amount of total suspended solids in this section of the Mississippi River.

The Mississippi River from U.S. Lock & Dam No. 1 in Minneapolis past Red Wing to the head of Lake Pepin is designated as the south metro stretch.

Too many suspended particles create cloudiness and unclear water. This prevents sunlight from penetrating the surface of the river and growing rooted aquatic vegetation for fish and wildlife to feed on.

But since the TMDL primarily focuses on reducing total suspended solids, there's still a concern of fixing other problems — such the levels of nitrogen and phosphorus — to improve the overall water quality.

"Total suspended solids are one dimension of water quality. There are many others," MPCA project coordinator Norman Senjem said. "Once you get into this you realize the need to focus on one thing in order to follow through."

Implementing TMDL will involve controling ravine erosion, managing water levels and building islands.

"We know the standards in this cleanup plan are within our reach," National Park Service resource director Lark Weller said.

The standards can be reached, but it's no quick process. Now that the TMDL has been released, an official public comment period will open this spring, and then the MPCA will be able to make revisions to the TMDL based on comments received.

Comments are encouraged from anyone, whether they favor or oppose the plan.

"The MPCA needs to hear from everyone and know this is a project they should move forward with," said Trevor Russell of Friends of the Mississippi River, a group working to protect the river and its watershed in the Twin Cities area.

A final report must received Environmental Protection Agency approval before the many years of implementation can get under way.

"There are going to be challenges, and this is going to go on for a while until we meet those challenges," Senjem said.

Successful implementation of the TMDL will not only benefit the south metro Mississippi, officials said, but also Lake Pepin, which the Mississippi - and its sediment - flows into.

If high levels of sediment continued to flow into Lake Pepin, experts say the head of the lake would fill in with sediment within this century, and the entire lake within 300 years.

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