Upper Mississippi River Mussel Counts
The National Park Service and the Minnesota Department of Natural Resources (DNR) surveyed the 72 miles of Missisippi River and 4 miles of Minnesota River that constitute the Mississippi National River and Recreation Area. The Minnesota DNR began this important work with the Statewide Mussel Survey, during the 1999 field season. The statewide survey continued during the 2000 field season and in the 2001 season with the involvement of the National Park Service's Inventory and Monitoring Program.
During the 2000 field season, the DNR was able to sample a total of 60 sites along the metropolitan Mississippi River corridor. In 2001, 108 sites were sampled. A total of 13,589 live mussels were collected over the two survey years. Some species were found in one year and not in the other. Forty-two of Minnesota's 49 species were found in this stretch of river; 22 of those were live.
The results of these studies are very encouraging. The results are drastically different than what the U.S. Army Corps of Engineers and the National Academy of Science found when they sampled the Upper Mississippi in the late 1970's. Their original findings painted a dismal picture for the health of the river. In the 1970's they only found nine species of mussel in the area. With the rehabilitation of the Mississippi River, we have found 28 live species in this stretch of water. Where mussels currently can be found throughout the river corridor, 30 years ago, their range was restricted to just below Lock and Dam 1. With improved waste water treatment techniques, separation of sewer and storm drains, and restoration of habitat, mussels are making a comeback.
The graph "Mussel Survey Data" shows species that were present in numbers greater than 1% of the total mussels found.
Did You Know?
At Lake Itasca, the elevation of the Mississippi River is 1,475 feet above sea level. It drops to sea level at the Gulf of Mexico. More than half of that drop occurs within the state of Minnesota.