Wildlife Paradise

A natural treatment system in Uvalde, Texas, doubles as a nature sanctuary and a magnet for birdwatchers and students.
Wildlife Paradise
Black-bellied whistling ducks are among visitors to the nature sanctuary at the Uvalde Water Recycling Center.

The Water Recycling Center in Uvalde, Texas, treats an average of 1.7 mgd (2.5 mgd design) before discharge to the Leona River about 10 miles away. Along the way, it serves as a virtual outdoor classroom for students and visitors and as home to thousands of migratory and nesting birds and other wildlife.

Located next to the 200-acre Cook’s Slough Nature Park, a popular southwest Texas birding destination, the plant polishes effluent in 12 acres of constructed wetlands. Complete with 8-foot-wide hiking and biking trails that meander for more than two miles throughout the wetlands, and with eight strategically placed wildlife viewing areas and rest stations, the park is rated by the National Audubon Society as one of the nation’s top 25 birding destinations. “It has become a great amenity for the entire community,” says plant superintendent Juan Zamora.

Designed for zero discharge with effluent used for irrigation, the plant was upgraded in 1987 to an extended aeration secondary treatment facility. Natural dechlorination is provided by two lagoons that were part of the old treatment system and whose outflow was periodically diverted into the slough to maintain its marshy habitat. But by 2000, increased demand for water reuse and tighter discharge standards challenged the discharge of any water into Cook’s Slough.

That’s when the city listened to Uvalde resident Ken Cave, owner of the Kenneth M. Cave and Associates environmental consulting firm. Cave’s vision was to develop constructed wetlands to improve water quality in Cook’s Slough and the Leona River, to insure a wetland water supply, and to provide waterfowl and wildlife habitat in an educational setting. “It took a long time to put all the pieces together, but we did it at a fraction of the cost of a new mechanical system that would have done the same job,” says Cave.

Grants from the Texas Park & Wildlife Service and Ducks Unlimited got the project off the ground. Cooperation and donations from many others supported the project. The city donated a 65-acre parcel near the treatment plant that has become part of the wetland park.

Visitors to the nature park navigate over boardwalks and footbridges to view birds like sandhill cranes, painted bunting, collard plover, and quail, as well as bobcats, blue indigo snakes and softshell turtles. Two 46-square-foot covered kiosks with concrete floors provide educational opportunities for students and nature lovers. A series of signs at the kiosks focus on nature study and environmental appreciation. Some define the various birds and wildlife, while others show how a natural wastewater system works. Displays also present tips for managing water usage and explain how an aquifer works.

“The signs were provided by the Edwards Aquifer Authority,” says Cave. “They describe the use of property and the value of wetlands.” The primary vegetation in Cook’s Slough is typical of southern Texas plains, with willow oak, hackberry, mesquite, clumps of sunflowers and sedges. A grassland portion of the slough is a reclaimed landfill that now serves as habitat for quail and other upland game. The constructed wetland units are on a reclaimed biosolids application site.

“It’s not a park that attracts campers and swimmers, but it is a major park for people who take their passive recreation seriously,” says Cave. “And it met our goal of improving the water quality, providing for water needs, and educating the public about water conservation.”


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