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Statewide mussel survey and watershed work leads to stream segments coming off impaired waters list

COGGON — Canary in the coal mine? In Iowa, we have the mussel in the stream.

Iowa’s freshwater mussels depend on good water quality and proper habitat, as well as waters that support healthy fish to carry baby mussels (glochidia) to their future homes. So the number and types of mussels in an area – or the lack of – can tell you a lot about the health of a stream or river.

In Iowa, they’ve told DNR researchers a lot.                          

Buffalo Creek, a tributary of the Wapsipinicon River, flows from Fayette County southeast to Jones County. Along that stretch, five segments sat on Iowa’s impaired waters list since 2008 due to problems supporting aquatic life – specifically, mussels. A 1984 survey showed a healthy number and variety of mussels in the stream, but by 1998, follow-up work found those numbers had dropped by more than 50 percent.

In 2010, local communities came together through the Upper Buffalo Creek Water Quality Project, headed up by the Buchanan Soil and Water Conservation District, to make changes on the land to improve the water flowing into Buffalo Creek. A similar effort through the Middle Buffalo Creek project added work downstream. Landowners and farmers created grassed waterways and filter strips, and used farming practices like planting cover crops to reduce erosion and runoff to the creek.

It made a difference. It reduced the amount of sediment reaching the creek by 4,417 tons a year – enough soil to fill 316 dump trucks. With that extra soil being kept out of the creek, mussels bounced back with improved habitat.

“Farmers and landowners really came together, and as a result, we have found threatened species where they weren’t before and are taking five stream segments off the impaired waters list,” said Chuck Gipp, DNR director.

A new DNR statewide freshwater mussel survey, which ran from 2011 to 2017, found a significant increase in Buffalo Creek over the 1998 survey, including four species of mussel that are on Iowa’s threatened species list. Many of the mussels were younger than five years old, suggesting that conditions had recently improved. As a result, five segments of Buffalo Creek were removed from the state’s impaired waters list for their aquatic life impairment, joining seven other stream segments in the state.

In addition, the old Coggon low-head dam was removed through the DNR’s Low-Head Dam Public Hazard Program, which will improve not only access and safety for canoeing and kayaking, but will benefit mussels and fish as well.

“The pool behind the dam was heavily silted in, but Linn County’s Buffalo Creek Park just upstream has river access and a nice little campground,” said Nate Hoogeveen, River Programs Coordinator for the Iowa DNR. “When people catch on that they can float downstream of the park, go through a short rapids and access to the pretty rock cliffs along Buffalo Creek below Coggon, they will have a great time camping, paddling and inner tubing in this area. People love this size of little river. It’ll bring visitors to town and adds an amenity to our state.”

DNR Fisheries staff anticipates improvements to fishing as well. “It will take around two to five years to see how fish populations fully respond to the water quality and fish passage improvements,” said Dan Kirby, biologist in the DNR’s Manchester fisheries office. “We expect to see some fish species that were formerly found only in segments below the Coggon Dam will now be found in upstream segments in Delaware and Buchanan County, including smallmouth bass.”

Statewide, the DNR sampled 813 sites over seven years as part of the freshwater mussel survey, finding 39 different species, including two that had been believed to have been gone from Iowa. Prior to the current statewide survey, 25 segments of Iowa streams and rivers were listed as impaired for freshwater mussel declines. As a result of the mussel survey, 12 segments have now been delisted, and another two segments will be proposed for delisting. The DNR also used the survey data to develop a biotic index to more accurately assess the condition of mussels in Iowa’s streams and rivers. The survey was funded through the DNR’s Watershed Improvement Program and U.S. Environmental Protection Agency Section 319 funding.

“We’ll use data from the survey to make decisions about removing low-head dams and for wastewater permitting,” said DNR biologist Jen Kurth, who led the survey. “We’ve also identified areas that are good candidates for protection based on the excellent mussel beds.”

Learn more about the Buffalo Creek project from the EPA, which selected the project as one of its featured success stories: https://www.epa.gov/nps/nonpoint-source-success-stories-iowa

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