Mississippi River, MO & IL - Improving aquatic vegetation conditions through dam operations
The Upper Mississippi River nine-foot navigation channel was authorized in 1930. By 1940, 25 locks and dams were built to maintain high water by impounding the river from Minneapolis, Minnesota, to St. Louis, Missouri. This change altered river connectivity and created water pools behind dams with more stable water levels in contrast with variation in a natural river system. Many ecological factors degraded over the years. By the late 1980s, aquatic vegetation was in severe decline or near collapse. Healthy river ecology is closely tied to the abundance and diversity of aquatic plants.
River managers and scientists sought options to restore this vital ecological component. They knew if water levels could be managed slightly lower during the growing season, the natural seedbank would respond on the exposed mudflats and river edge. In 1994, the Corps and stakeholders came to an agreement to manage water levels 1-2’ lower for 30-40 days when hydrologic conditions would allow for both navigation and improved ecological conditions. Since then, the Corps has continued and enhanced this management practice.
Mel Price Pool - Regenerated vegetation provides forage for migratory Tundra Swans and ducks in Mel Price Pool (photo by Benjamin McGuire, USACE).
Mel Price Pool - Common arrowhead returns to Mel Price Pool in a backwater area near Alton, Illinois. Beds of this perennial plant are present as a result of changes in dam operations during the summer growing season (photo by Benjamin McGuire, USACE).
Mel Price Lock and Dam - Light green vegetation along the river’s edge is newly regenerated as a result changes in summer dam operations at Mel Price Lock and Dam during the early years of Environmental Pool Management (USACE photo).
St. Louis District Locks and Dams - Through Environmental Pool Management at Pools 24, 25, and Mel Price, over 1,500 acres of mudflats and river edge are exposed to grow native vegetation, providing direct benefits for aquatic and terrestrial species and indirect benefits of improved water quality and bank stabilization (USACE photo).
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Story
Aquatic vegetation in the Upper Mississippi River nearly collapsed in the late 1980. Looking for solutions, river managers began to evaluate whether regaining some seasonal variability in water levels could regenerate the aquatic plant community. Historically water levels would rise in spring with snow melt and spring rains and fall off during the summer growing season and these seasonal changes create optimal conditions for plant germination and growth. Lock and dam operation hold water levels higher in the summer months for commercial navigation, degrading conditions necessary to maintain plant communities. Read More
Partners
- Illinois Department of Natural Resources
- Missouri Department of Conservation
- Missouri Department of Natural Resources
- River Resources Action Team
- The Nature Conservancy
- U.S. Army Corps of Engineers, St. Louis District
- US Fish and Wildlife Service - Endangered Species and Refuges
- Various other NGOs and private groups
Resources
- Garvey JE, Dugger BD, Whiles MR, Adams SR, Flinn MB, Burr BM, and Sheehan RJ. 2003. Responses of fishes, waterbirds, invertebrates, vegetation, and water quality to Environmental Pool Management: Mississippi River Pool 25. Reports. Paper 4.
- Benjamin GL, Rogers AJ, and Killgore KJ. 2016. Mississippi River ecosystem restoration: The past forty-plus years. American Fisheries Society Symposium 84: Chapter 15.
- Kenow KP, Benjamin GL, Schlagenhaft TW, Nissen RA, Stefanski M, Wege GJ, Jutila SA, and Newton TJ. 2015. Process, policy, and implementation of pool-wide drawdowns on the upper Mississippi River: A promising approach for ecological restoration of large impounded rivers. River Research and Applications. DOI: 10.1002/rra.2857.
Publications