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Using Recycled Edwards Water Use of recycled water from sewage treatment plants can defer large amounts of Edwards Aquifer pumpage during critical times, thereby helping to maintain springflow levels and preserve endangered species habitats. There are plenty of uses that do not require potable Edwards water, such as for irrigation of golf courses and parks, air conditioning cooling towers, and industrial processes. Recycled water contains small amounts of nutrients, so using it in irrigation can reduce fertilizer costs. In other applications such as cooling towers and industrial processes, some treatment and chemical additions may be required, but such is usually the case when potable water is used.
Although reuse can reduce Edwards pumping, it can also impact downstream users and ecosystems by reducing the flow in streams that otherwise would have received the effluent, so careful consideration of all impacts is warranted. Use of recycled water in Texas is classified as either direct, such as by direct delivery from the treatment plant through a pipeline, or indirect, such as delivered via the bed and banks of a river. Reuse In San Antonio: A Long History Few places in the United States have practiced reuse of wastewaters longer than San Antonio. As early as 1894, raw sewage was widely used in agriculture in fields south of town. By 1901, Mitchell Lake had been constructed to capture excess flows that could not be used. By the 1930s, a wastewater treatment plant had been constructed, and both raw and partially treated effluents continued to be delivered to farmlands and to Mitchell Lake through a network of ditches. In the 1960s, San Antonio pioneered an innovative use of recycled water in power production. After the drought of record in the 1950s, city leaders looked for ways to conserve potable Edwards supplies. Victor Braunig, then-general manager of City Public Service, the city's electrical generating utility, envisioned that large amounts of potable water could be saved if wastewater effluent was used to cool the city's power plants. Braunig Lake, first filled in 1963, was the world's first large-scale attempt to use recycled water for cooling electrical generating plants. Initially there were some problems with algae and suds from high-phosphate detergents, and large balls of soapy foam were said to have blown across I-37 like tumbleweeds. But Braunig and his staff were determined to make it work, and it ended up working so well that Calaveras Lake was built in 1969. Braunig Lake covers 1,350 acres, and Calaveras Lake covers 3,550. In dry years, up to about 40,000 acre-feet of cooling water is consumed that would otherwise have to be drawn from potable supplies. The use is classified as indirect, and CPS withdraws the recycled water from a pump station on the San Antonio River after it is released by SAWS' plants.
The Nation's Largest Reuse System In 2000, the San Antonio Water System completed construction of the nation's largest recycled water distribution system. It's purpose is to move fully treated wastewater to locations where it can be beneficially used. Over 80 miles of trunk lines were constructed at a cost of over $140 million. It is classified as a direct reuse project, and water supplied for non-potable uses by this system can supply up to 35,000 acre-feet per year, about 20% of the volume that San Antonio currently withdraws from the Aquifer. Although reuse is encouraged by the Texas State Water Plan, the state's rules and regulations have not caught up with the 21st century, and SAWS has been unable to obtain permits from the Texas Commission on Environmental Quality that would allow full utilization of the reuse system. SAWS Recycled Water Distribution System In addition to supplying water to customers for non-potable uses, the SAWS' project was constructed as a unique dual-use system that also involves augmenting the flow of several area waterways. As such, it is one of the largest environmental protection and enhancement projects ever conceived and constructed in the state of Texas. On the San Antonio River in the downtown area, construction of three new discharge points allowed several Edwards wells to be shut off that for many decades had been supplying all the dry-weather flow to the River Walk. A fourth discharge on Salado Creek has re-established a baseflow and created the foundation for a linear aquatic greenbelt (see the Salado Creek page). Since these discharges started, biologists have documented significant and lasting improvements to the aquatic ecosystems in both the San Antonio River and Salado Creek.
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