dam

Jul 28, 2016

Saving Endangered Mussels in Missouri’s Big River

dam, endangered species, freshwater, lead contamination, Mussels, rivers, Sediment, toxic metals 2 Comments

By Cody McLarty

When you want to spend a relaxing day outdoors in the Heartland, few places are more peaceful than Rockford Beach Park, just northwest of House Springs in east central Missouri. A low head dam, built in the late 1890s to power the now nonexistent Rockford/Bonacker Mill, still stretches partway across the Big River. This aging dam creates a tranquil waterfall that has enticed patrons of the Jefferson County Parks system for decades.

Photo of old Rockford/Bonacker Mill, near present location of Rockford Beach Park. (Courtesy of Jefferson County, Mo. Library, Northwest Branch, Special Collections)

Other patrons of the Big River also enjoy the benefits provided by the Rockford Beach dam: a vast, diverse community of freshwater mussels. Yet, unbeknownst to many, just below the babbling waters of the Big River, these abundant mussel species are becoming more endangered every day.

A visual inspection of the dam conducted by the Missouri Department of Natural Resources (MDNR) in January 2015 found that it had experienced heavy deterioration and was in a state of partial failure. Sections of the stone had washed away, leaving voids beneath the surficial concrete shell. Moreover, MDNR noted that if no action was taken, the dam would eventually experience a total breach.

EPA was placed in charge of this project because if the dam were to fail completely, it would result in the release of stored sediment behind the dam, which is contaminated with mining-related metals, and just 200 yards downstream from the Rockford Beach dam are three federally-listed, endangered mussel beds.

Eastern portion of Rockford Beach dam

I’m a remedial project manager in the Special Emphasis branch of the Superfund program at EPA Region 7, and was assigned to the Rockford Beach dam project in September 2015. I had been working with the U.S. Army Corps of Engineers (USACE) on several other projects through interagency agreements, so I was familiar with the process and had pre-established contacts within the USACE in the St. Louis area.

A 2009 study of freshwater mussels throughout the Big River found a total of 2,198 living specimens representing 33 unionid species at 19 study reaches in the river. Nine species of state conservation concern were found, including three federally-listed species (Pink Mucket, Lampsilis abrupta; Scaleshell Mussel, Leptodea leptodon; and the recently listed Spectaclecase, Cumberlandia monodonta). The majority of the mussel population in the Big River occurs downstream from the Rockford Beach dam.

A breach or failure in the remaining section of the dam would release trace elements of lead, arsenic, barium, cadmium and zinc – all elements routinely found around older mining and industrial sites. As benthic, filter-feeding organisms, freshwater mussels are directly exposed to contaminants in sediment and surface water.

That kind of significant release would severely impact a large number of freshwater mussel species located downstream, and the Big River has an incredibly diverse mussel community.

Apart from biological impact to the endangered mussel beds, the failure of the Rockford Beach dam could present a myriad of other environmental and safety issues to the surrounding area. That contaminated sediment, if released, would be made available downstream to the floodplain and further into the Meramec River. Those deposits could disperse a concentrated volume of lead into the environment, making it a much larger problem to remediate in the future.

Construction to stabilize western portion of Rockford Beach dam

In January 2016, EPA entered into an Interagency Agreement (IAG) with USACE to conduct a removal action to stabilize the western portion of the dam. The eastern portion of the dam had already partially failed, which now allows for fish passage. This partial failure was not significant enough to cause the release of built-up contaminated sediment. Under the IAG, the USACE planned, designed, and constructed an interim solution to stabilize the western side of Rockford Beach dam.

Many other state and local agencies provided support to the project, including local fire and police departments, the U.S. Fish and Wildlife Service, Missouri Department of Conservation, and MDNR’s Dam and Reservoir Safety Program.

In Superfund, we often work on projects that can span a lifetime, so it’s nice to be able to start a project, see it run smoothly, and witness the completion. It’s not often that you get to work on a project that allows you to build strong and lasting relations with a community, and at the same time, protect and safeguard endangered species.

About the Author: Cody McLarty serves as a remedial project manager in EPA Region 7’s Superfund program. He mainly works in the southeast Missouri mining district. Cody has a bachelor’s degree in conservation biology from the University of Texas at Austin, and a master’s degree in engineering management from the University of Kansas.

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Sep 24, 2012

Lassoing a Whirlwind: Managing Flow on the Missouri River

dam, Flooding, gavins point, missouri river, Sturgeon, water 0 Comments

By Larry Shepard

When Casey and Jeff asked me to write a blog entry, I was staring at my screen saver which was a picture of a lake sturgeon isolated by the dramatic draw down of the river below Gavins Point dam near Yankton, South Dakota. Along with its more famous cousins, the pallid and shovelnose sturgeons, the lake sturgeon is a prehistoric fish struggling to survive in the altered environment of today’s Missouri River. How this interesting “Jurassic Park” specimen ended up in a pool of water in the Missouri River for folks to gawk at makes for an interesting story.

Photo courtesy South Dakota Department of Game, Fish and Parks

It’s been an awfully dry summer this year but during the Summer of 2011, the Missouri River basin was saturated from a Spring rain, particularly the upper basin in North Dakota and Montana. Combined with a high snow pack and late season snows in the mountain ranges feeding Great Plains streams, atypical Spring rains produced record amounts of runoff into the six reservoirs managed by the Army Corps of Engineers.

In an effort to protect the infrastructure of the 1950s and 1960s era constructed dams holding back all this excess precipitation and to prevent dam over-topping and possible catastrophic failure, the Corps released water downstream into the lower basin. Normal releases from Gavins Point (the southernmost dam) in mid- Summer are typically about 32,000 cubic feet per second (cfs), but in July 2011, Gavins passed about 160,000 cfs. That amount of water had never been released through the dam and its impact on the dam structures was unknown.

The resulting high water levels innudated the floodplain, displacing residents and damaging crops and property. Levees built to restrict the river to a narrow channel could not hold back the larger volumes of river water, particularly those levees constructed close to the river bank creating ‘pinch points’ for river flow. Repeated failure of several levees, particularly at ‘pinch points’, during multiple high water events has caused the Corps to begin consideration of levee ‘set-backs’ to address an unsustainable levee design which would also open up the floodplain to accommodate more river flow and improve aquatic habitat.

Photo by Larry Geiger

Fast forward to early 2012, and the volume of releases from dams raised concerns about possible damage to structures, and the Corps determined that close inspection at particular locations to verify condition and assess any damage was necessary. This was the case at Gavins Point near Yankton, South Dakota where the Corps actually closed the spillway in order to allow inspectors to assess damage. That is, no river water flowing through the dam, resulting in an extreme photographic contrast from the Summer of 2011.

Photo courtesy of South Dakota Department of Game, Fish and Parks

When the dam was closed in May 2012, the reach of the river extending down almost to Sioux City was transformed, exposing natural and man-made features not seen since the dam was finished in 1955. River organisms were stranded, including many mussels, not commonly found in the lower river.

Photo courtesy of South Dakota Department of Game, Fish and Parks

River scientists know how the lower river’s substrate is dominated by ‘dunes’ of sand which roll and jump along the bottom which was unique to see firsthand. These ‘waves of sand’ create a very dynamic environment for aquatic organisms living in the sediment and coasting above it. It also presents challenges for human engineering to adapt river structures to a moving bottom.

Photo courtesy of South Dakota Department of Game, Fish and Parks

If you are ever in the vicinity of any of the six big Army Corps dams on the Missouri River, call the Corps office at the dam and see if there’s an available tour of the facility. They are each unique in their design and how they are placed in the ‘natural environment.’ My personal favorite is Fort Peck dam near Glasgow, Montana, the uppermost dam operated by the Corps. It was constructed in the 1930s during the Great Depression and its powerhouse has an ‘art deco’ design.

Larry Shepard is an environmental scientist in EPA Region 7’s NEPA program reviewing environmental impact statements and environmental assessments primarily focusing on river-related federal projects. Shepard hails from the shores of Beal Slough in Lincoln, Nebraska, which flows to Salt Creek, then to the Platte River, then to the Missouri River and finally to the Mississippi River.