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USACE Partners with The Nature Conservancy to Enhance Environmental Conditions on Lower Roanoke River

Published March 14, 2017

     In 2002, the U.S. Army Corps of Engineers (USACE) and The Nature Conservancy, formed a partnership and established the Sustainable Rivers Project (SRP).  The SRP focuses on modifying water operations at USACE dams to enhance the habitat conditions for plants and animals who depend on downstream river flows. 

    SRP activities are occurring in eight river basins throughout the U.S., making it the largest coordinated effort of its kind in the world. Currently, the Roanoke River is one of the basins focusing on defining environmental strategies as part of a water management plan.  At SRP sites, scientists gather data on the river flows and work with water managers to modify dam and reservoir operations within existing water control policies and manuals for each reservoir.                

   USACE reservoirs affect the timing and magnitude of river flows to meet the competing needs of both human and environmental impacts. The reservoirs generate increased benefits by improving fish migration and water quality, flood damage reduction, and hydropower while also supporting navigation and recreation.

   One of the largest and least disturbed Bottomland Forest Systems on the Atlantic Coast the lower Roanoke River floodplain is approximately 137 miles long, and up to five miles wide and additionally one of the largest and least disturbed Brown Water River Systems in North America. Furthermore, its 31 natural communities provide habitat for two federally listed animals, 16 state listed animals, 13 state listed plants, and 214 bird species, 88 known to nest including 44 neo-tropical migrants and several heron rookeries. Also, the Roanoke has the most diverse and significant populations of migratory fish on the Atlantic Coast of the U.S.

   The TNC Roanoke River Project started in 1982 with a donation from Union Camp Corporation of 176 acres of land.  Since that time, TNC along with various partners have conserved approximately 95,000 acres along the river, its floodplain and in the surrounding watershed. The majority of these lands are managed in the public trust and or recreational use by the North Carolina Wildlife Resources Commission and the United States Fish and Wildlife Service.  As the TNC Roanoke River project grew they reached out to other stakeholders.

    “One of the things that led us to a successful outcome is everyone who is concerned with recreation on the river, came together and said, ‘We need to coordinate among ourselves in a more unified voice to USACE,” John Morris, former director of North Carolina Division of Water Resources said. “Starting in 2014 this stakeholder group really took hold and we had many meetings with USACE. We did some coordination with ourselves and gave USACE a more unified partner to work with as they were looking at different ways to improve the operation of Kerr Lake.”

   It became apparent that the USACE operation at Kerr would need to be modified.  John H. Kerr Dam and Lake has been in place a long time – more than 50 years – and has played a pivotal role in the life of the Roanoke Valley.

   “We have shaped our operations regime, as we usually do, to optimize the dams many authorized purposes and in accordance with prevailing conditions (flood, drought, etc.).   But as we began our work with TNC and our state partner in North Carolina we could see that there were additional opportunities to enhance operations and improve conditions for the floodplain ecosystem,” Col. Kevin P. Landers, Sr., USACE, Wilmington District Commander said.

   “The Roanoke River begins in the mountains, comes through the Piedmont, and ends here on the coastal plains, and empties out into the sound. The coastal plain reach is the most significant part of the river because it’s your typical alluvial flood plain. You have the levee, you have the swamp area, you have the high ridges, and you have the low ridges.  The diversity that you’re going to find here is just unbelievable,” Jean Richter, biologist with the USFWS said.

   The floodplain on the lower Roanoke River is considered one of the largest intact and least disturbed bottomland forest ecosystems remaining in the mid-Atlantic region. The unique thing about this river is the floodplain is still very active because there’s not a lot of development. We have a pretty intact floodplain as far as the forest goes. So you’re going to have a forest in all stages of growth.  Some cutting has occurred so you’re going to have early forests, and you’ll have nice mature hardwood forests, and then you’re going to have areas in between,” Richter said.

   A change at any USACE dam requires a 216 study, and through modeling and review of historic river flows USACE came up with an alternative that more closely mimics the natural variations of the river. This alternative, known as QRR, or quasi-run-of-river, is the operational paradigm for releases out of Kerr Lake today.

   “Working with USACE, we came up with an optimal solution where the plan kicks in only when Kerr Reservoir is in flood control operations and it allows USACE the flexibility to send a bit more water downstream, but within the way the dam was designed to operate. So USACE is able to maintain its flood control operations and the river gets the sustaining flows that it needs at the same time,” Chuck Peoples, the director of conservation, North Carolina Chapter of Nature Conservancy said.           

   “A 35,000 cubic feet per second (cfs) flow, which is the maximum flow that you can release under QRR, flows through this forest and it’s quickly gone. Flows of significantly less than 20,000, say in the neighborhood of 11,000 cfs, don’t make it over the levees so they stay in the river.  However flows around 20,000 cfs flood the forest and as the water continuously sits there it gradually loses all of its oxygen. Additionally the temperature goes up and it becomes more acidic and the trees gradually die along with many other things dying simultaneously; all of the box turtles that couldn’t move away, the lizards and the salamanders, the ground nesting birds such as wild turkeys.  Even the wasps that control the forested caterpillar populations and they all have ground stages and they all get killed when water sits at 20,000 cfs for a long time,” Sam Pearsall, member of board of science advisers, Roanoke River Basin Association, and the former director of science, Nature Conservancy said. 

   QRR will significantly reduce the frequency and severity of bank collapse, preventing further degradation of fish and aquatic habitat and reducing the rate of shoreline land loss. 

   “The concern we have with erosion is the banks become vertical.  When you have vertical banks there are actually bird species using the banks for forage and they can’t use those banks or use a vertical bank.   When the river is at flood stage they can actually use the vegetation along the banks as refuge. But if you have a vertical bank with no vegetation, they have no place to go to.  So what happens is the river starts looking like a bathtub; banks with no vegetation and wildlife can’t use it anymore. That’s why we’re trying to preserve what we have left with the vegetation on the banks so the wildlife can continue to use it, aquatic life in the river can use it as refuge to escape from predators and as feeding areas, too, and nursery areas,” Richter said.                   

   “You can’t find forests like you find in the Roanoke River basin across the United States like you perhaps could a hundred years ago.  I think it’s important for us as a nation to make sure that we’re being good stewards of our environment that we live around,” Landers said.

   Landers further elaborated, “We have to try and strike a balance that both meets our project’s intent, but also incorporating into that solution, the environment, and the needs of the stakeholders.  There’s a whole myriad of different angles that have to be looked at and addressed in coming up with the optimum solution.  Sometimes we don’t ever reach the optimum solution, but at the end of the day we’re definitely trying to strike a balance among the stakeholders by collaborating and understanding their needs.”