By Jennifer Boudart
Ducks Unlimited has a unique mission: to conserve, restore, and manage wetlands and associated habitats for North America's waterfowl. DU is well positioned to carry out that mission, thanks to the support of its members, the strength of its partnerships, and the broad expertise of its staff. In fact, DU is unique among conservation organizations in its ability to offer turnkey services for wetland projects.
Key to DU's conservation work is an in-house staff of civil engineers, surveyors, and technicians. These professionals work to integrate wetland ecology into engineering by performing site surveys, conducting soil and hydrology analyses, creating engineering designs, and providing construction management. They work very closely with DU biologists, who provide the knowledge and experience needed to craft the best solutions for the biological aspects of a project.
"Given our expertise, we serve a useful niche for partnering agencies," says Kerry Scott, senior regional engineer for DU's Great Lakes/Atlantic Region (GLAR). Scott notes that many state agencies and conservation organizations lack full-time engineers, so DU can offer a much-needed skillset.
That has been true for DU's partnership with the Missouri Department of Conservation (MDC). In 2004, the MDC launched its Golden Anniversary Wetland Initiative, an effort to rehabilitate and enhance wetlands on its five oldest wetland conservation areas. DU has been an important partner in this initiative, especially when it comes to providing innovative engineering solutions.
One major focus of the initiative has been Duck Creek Conservation Area, located in the Mingo Basin. Duck Creek is an important wintering and migration area for waterfowl and other migratory birds. It also provides valuable areas for waterfowl hunting and fishing. Renovations at Duck Creek took place in three phases. Scott was involved in the renovations and says phase one is a good example of the type of engineering work in which DU specializes.
Phase one involved reconfiguring 1,450 acres of moist-soil habitat in two managed units. Infrastructure put in place there 60 years ago was no longer effective. Contributing factors included outmoded systems of levees and ditches, equipment that had exceeded its life expectancy, and changes in surrounding land use that caused more frequent and more intense flooding.
"When these conservation areas were established, we didn't have the wetland engineering technology or ecological understanding that we do today," Scott notes. "The older designs were these big rectangular pools that really didn't fit the landscape. They held water but didn't always provide the proper food and habitat for the targeted species. The old designs didn't always use water efficiently and did not perform well during floods."
"We took a holistic look at these old wetland complexes," says Mark Flaspohler, GLAR director of conservation programs. "We wanted to use updated wetland engineering and design to bring some natural hydrology back on the landscape. That would help create a wetland system that functioned a little more like Mother Nature intended, but that could still be effectively managed."
Planning the engineering design involved observing old aerial photos as well as topographic images derived through LIDAR (Light Detection and Ranging) technology to better understand the natural flow of water across the landscape. This information helped identify old slough signatures where the water used to flow. "We wanted to bring back those historical water features, to reconnect to that natural hydrology," Scott explains. Design development also included running high-flow models to simulate possible impacts of different-sized storm events. The final design was delivered as a digital file that computer-controlled machines could use to precisely scrape and shape the earth as needed.
Construction involved reconfiguring a lot of the original infrastructure. For example, many of those old, meandering sloughs had been cut off and bypassed with straight ditches. While straight, deep, steep-sided channels may have been efficient at conveying water, that water traveled at high velocities and created chronic flood-damage problems. "We needed to reestablish some areas for floodwater to more gradually spread out, as it would in a natural floodplain, rather than a ripping conduit taking the water on downstream," Scott says.
An example of this was the filling of a mile-long section of ditch running through the project area and its replacement with a much shallower, meandering two-mile stream. Stream banks were built to be low and sloping, so floodwaters could easily pass over them before gradually spreading across the adjacent land. The new watercourse also provided four times more stream bank habitat for shorebirds and other aquatic animals.
Shallow wetland habitat quality increased as old slough fragments were reconnected to a broader network of created channels across the area. Water from the sloughs could be used to gradually flood the habitat in fall, and the sloughs would still hold water during summer drawdowns. Once planted with native aquatic plants, the sloughs would also increase habitat diversity and refuge for aquatic animals that don't seasonally migrate.
Construction also involved reconfiguring levees. Their traditional design—tall, with steep sides—made them vulnerable to erosion and flooding. In many cases, their placement was at odds with the land's natural topography and hydrology. Scott says more than 10 miles of levees were rebuilt as shorter, broader, more gently sloping levees placed along natural land contours. The new levees are more resilient during flooding and create a better distribution and range of shallowly flooded habitats. Once revegetated, this revamped infrastructure blended in better and provided valuable transition habitat.
Additional work included creating spillways along the levees to better protect against high rainfall events and installing two wells to provide water during droughts. Soon after phase one was completed, both of these climatic extremes occurred, and the environmental engineering designs were put to the test. The area responded to both flood and drought positively thanks to the recent improvements. Today, the reconfigured habitat supports healthy numbers of migrating and wintering waterfowl along with more shorebirds, fish, and amphibians. It also provides new opportunities for hunting.
Recently, the Duck Creek Conservation Area Renovation Project was recognized with the Carl V. Anderson Conservation Project Award, 2019 Award of Excellence, by the Association of Conservation Engineers.
By the Numbers
Conservation work done during phase one of the Duck Creek Conservation Area Renovation Project in Missouri is already making a difference for wildlife. Here's a quick overview of the project's accomplishments and partners.
Size: 1,450 acres
Cost: $3.2 million
- Eight miles of borrow pits and field ditches filled in
- More than 10 miles of steep-sloped levees reconfigured to create broader, shorter levees along natural land contours
- One mile of ditch removed to restore a two-mile meandering stream
- Two miles of existing slough fragments reconnected, tied into a 16-mile network of scours
- Two new wells installed to enable flooding of an additional 290 acres of habitat
Ducks Unlimited, Wetlands America Trust, Missouri Department of Conservation, Mingo Swamp Friends, National Wild Turkey Federation, Audubon Society of Missouri, Missouri Conservation Heritage Foundation, Missouri Bird Conservation Initiative, Missouri Department of Transportation, Conservation Federation of Missouri, Conservation Employees Credit Union, Cato Slough Hunting Club LLC, Greenbrier Wetland Services