Chain of Wetlands
The Dallas Floodway Extension (DFE) Project includes a Chain of Wetlands component that provides for flood protection and environmental restoration.
The Chain of Wetlands extends about four miles in length from Cedar Creek to Loop 12. The system is comprised of seven wetland cells that all together produce 170 acres of water surface. About 100 acres of grasslands will fill in between and around the wetland cells. The three wetland cells located between Cedar Creek and Interstate 45 are interconnected and actually flow upstream as they will be continuously fed by discharge (or treated water) from the Central Wastewater Treatment Plant (CWWTP). The plant's water is treated against harmful bacteria before being discharged. A fourth wetland cell located just downstream of Interstate 45 will act independently as CWWTP treated water will pass through and directly into the Trinity River. The remaining three wetland cells will extend from the Interstate 45 vicinity to Loop 12 and also be interconnected and continuously fed by CWWTP water.
Wetlands Location Map (click here to view larger image)
The Chain of Wetlands were strategically placed along the west side of the Trinity River in areas that would provide for the least impact to existing trees. The Chain of Wetlands average about 600 feet in width and offer a secondary route for flood waters when the Trinity River is in flood stage. This increase in flood conveyance not only offsets the adverse effects of the levee components of the DFE Project, but further results in a lowering of flood elevations for the southern Trinity River corridor and the existing Dallas Floodway. With the DFE Project in place, the Dallas Floodway will once again be able to protect the downtown Dallas vicinity against the Standard Project Flood (SPF).
Another purpose for the Chain of Wetlands is to provide for environmental restoration for the Trinity River corridor. Wetlands have historically been reduced along the Trinity River corridor due to man-made corridor development. Each of the wetland cells will include a control structure that will allow for management of water surface elevations that can be raised or lowered on a seasonal basis to maximize the ecological and wildlife output. The wetland cells will have multiple shelves to produce shallow water depths to maximize the development of quality wetland plants and wildlife species. The DFE Project will also include about 31 miles of trail system that will provide public access to the Chain of Wetlands for environmental interpretive value and wildlife observations.
A wetlands design summary for the Chain of Wetlands was produced as part of an inter-agency and citizenry team that worked together for several months during late 1999 and early 2000. The team included the U.S. Army Corps of Engineers, Environmental Protection Agency, U.S. Fish and Wildlife Service, City of Dallas staff, Texas Parks and Wildlife Department, and the Trinity River Corridor Citizens Committee (TRCCC). The Corps of Engineers expertise included Dr. Michael Smart who specializes in wetlands research at a lab located at Lewisville Lake. Dr. Smart and his colleague Gary Dick authored "Dallas Floodway Extension Wetlands: A proposal for establishment of native aquatic vegetation", as part of the inter-agency collaborative work for the final design of the Chain of Wetlands. View photos of a wetland cell designed by Dr. Smart.
During 2002-2003, Bryan Kilburn of the Trinity River Corridor Project conducted tree surveys for the footprint of wetland cells A, B, C, and D. The purpose was to assess the tree species population and size in order to determine the potential loss of mast producing trees (pecan, oak, etc) as part of the construction of the wetland cells. No mast producing trees were found where these wetland cells will be located. The tree assessment (13.6 MB, this is a large pdf file) also compares the nature of the forest as it was in 1949.
If you need more information about the Chain of Wetlands planned for the Dallas Floodway Extension Project, please contact the Trinity River Corridor Project Management Office by calling (214) 671-9500, or via email.