Extreme erosion along the lower Osage River has produced a host of problems for the waterway and the environment around it. River conditions diminish endangered aquatic species, cutting into banks of private land and destabilizing the riverbed.
State and federal agencies are taking note.
The Missouri Department of Natural Resources is partnering with the U.S. Army Corps of Engineers on two multi-year projects to address severe erosion and restore aquatic ecosystems for several endangered species.
Efforts include an 80-mile river investigation survey and a feasibility study of a river site near Brockman Springs Road in Miller County.
By addressing bank erosion and sedimentation along the lower Osage River, MNR and the Corps hope to restore degraded aquatic and riparian habitats, promote fish and wildlife biodiversity, and reduce negative impacts of erosion on nearby land and infrastructure.
Jeffry Tripe, project manager for the U.S. Army Corps of Engineers Kansas City District Environmental Program, said the site-specific study, which he referred to as a Permanent Authorities Program Section 1135 project, will take place in three phases, starting with a feasibility study.
The study will assess issues along the river near Brockman Springs Road, develop restoration measures to address these issues, and produce a recommended plan with alternatives that provide the most value to ecosystems relative to the cost of implementation. .
After approval of the feasibility study, the project will move into a design phase to further develop details and specifications for implementing the recommended plan, Tripe said.
From there, the recommended plan would be implemented through a construction contract and the Army Corps of Engineers would return the site to MNR for operation and maintenance.
In addition to the Section 1135 project at Brockman Springs Road, the Army Corps of Engineers and DNR are partnering on an investigative study over the next few years to address systemic ecosystem issues in the lower portion of the the Osage River.
At about 82 miles, the Lower Osage River meanders through central Missouri from Bagnell Dam at Lake Ozark to its confluence with the Missouri River near Bonnots Mill.
Several ecosystem issues have been identified in this stretch of river, Tripe said, and many stem from bank erosion.
“There is a serious erosion problem,” said Tim Rielly, a biologist with the Missouri Department of Natural Resources.
Rielly said local landowners are concerned about loss of shoreline due to erosion, which also affects the lower Osage River when they feed there.
He said understanding how the Osage River degrades the land around it is a priority for the state agency and landowners.
In addition to severe bank erosion, Tripe said, the lower Osage River is experiencing widening of the downstream channel, riverbed instability and barriers to aquatic species migration. The river also poses increased risks to surrounding infrastructure and life safety risks, he said.
Tripe said channel and bank degradation is reducing the quantity and quality of riparian and aquatic habitats in the lower Osage River, and the continued loss of aquatic habitats is negatively affecting several endangered mussel and fish species. and endangered.
The lower Osage River is home to four species that the U.S. Fish and Wildlife Service considers threatened or endangered: pink clams, shell clams, spectacle clams, and pale sturgeon.
Erosion of stream banks and changes to the river channel destroy habitats and reduce fish spawning and mussel reproduction, Rielly said.
Tripe said the problems in the lower Osage River are the result of upstream reservoirs altering hydrology and water movement, variable flows resulting from hydroelectric generation from Bagnell Dam and the Generating Station in ‘Osage, structures inherited from the watercourse and obstructions to secondary channels.
These factors are contributing to the widening of the river, Rielly said, and part of the study’s analysis will determine its expansion where the greatest erosion has occurred.
Tripe said site and helicopter surveys, reviews of historical mapping, LiDAR, hydrological and hydraulic modeling and bathymetry (the study of water depth) were used to confirm degradation of the lower Osage River.
The information obtained from these measurements will be used to document the existing conditions of the river, Tripe said, and to project what the river will look like in the future if the issues are not resolved.
The $3 million study, split 50/50 between the DNR and the Corps, will take about three years and at least a dozen people, Rielly said, including engineers, hydrologists and biologists.
After the study, the U.S. Army Corps of Engineers must approve the construction design plans to make it eligible for congressional funding, which would cover 65% of construction costs.
Tripe said the first step in the Lower Osage River Feasibility Study is to identify and assess restoration measures that could potentially be implemented.
To combat erosion, Tripe said, agencies are considering, among other measures, bank sloping and bank cuts with planting, planting alone, hard structures like riprap (a layer of rock to arming the bank soil), notching of legacy structures, dredging (removal of silt and material from the river bottom) and features to support the natural flow of the river.
Steps agencies can take to support threatened and endangered species in the river include stabilizing existing mussel beds and habitats, improving side channel flow, and increasing connectivity by tackling to erosion and water barriers, Tripe said.
Tripe said the recommended potential plan resulting from the feasibility study can include any combination of these site-specific measures.
“During the feasibility phase, conceptual cost estimates will be developed for viable alternatives to identify the most comprehensive, efficient, effective and publicly acceptable implementation plan,” he said.
Reduced erosion and limited sediment accumulation in the lower Osage River is expected to deepen the depths of the main and side channels over time and increase the depth and diversity of habitat in the course. of water, Tripe said, “which will benefit native aquatic species to include pallid sturgeon.”
The three endangered mussel species will also directly benefit from reduced sedimentation, he said, as better water quality reduces the likelihood of mussel beds being covered in sediment and provides new mussel dwelling areas.
By stabilizing river banks, Rielly said, the project is expected to have a positive impact on local landowners who are losing land to erosion and on the river ecosystem which has been negatively affected by the sediment increase.
“There will be a double benefit,” he said.
Rielly said the lower Osage River was selected for restoration due to habitat degradation and interest from landowners, MNR and elected officials, including Republican Congressman Blaine Luetkemeyer.
“Thousands of Missourians live along the shores of our state’s rivers, streams and lakes. I am committed to continuing my work on many important issues facing our water resources, including the degradation of canals and riverbanks, flood protection, navigation and property rights,” Luetkemeyer’s website states. “We need to focus on protecting life and property and keeping our levees safe and strong.”
Luetkemeyer, who represents Missouri’s 3rd District, is actively engaged with the federal Water Resources Development Act of 2022.
The legislation, which was approved by a congressional committee, aims to advance the Water Resources Development Act of 2020 which authorized 27 feasibility studies of water resources projects across the country. The 2022 version of the bill would authorize 72 new feasibility studies for water projects and direct the Army Corps of Engineers to expedite the completion of 14 feasibility studies already underway.
Additionally, restoration efforts are supported by cooperating agencies such as the U.S. Fish and Wildlife Service, Missouri Department of Conservation, Ameren, Natural Resources Conservation Service and the Environmental Protection Agency, Tripe said.
“If the proposed restoration is not carried out, the future without project conditions in the lower Osage will continue to degrade, resulting in continued erosion, decreased river and riparian corridor habitat connectivity, aggradation continues in the main and secondary channels and a decrease in the number of native and endangered species,” Tripe said.
This continued degradation would also mean more loss of private land for landowners, water quality in the river remains poor, infrastructure risks persist and there is increased potential for life safety risks, continued Tripe, which would also mean less recreational opportunities on the river.
“These are usually big problems that cost a lot of money to fix or mitigate,” Rielly said. “So it’s a study that provides solutions, not just a study to be studied, which isn’t a bad thing either.”