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One way to avoid the high cost of treating water is to reuse gray water. Gray water systems can be developed at the household level, re-using fairly clean water from washing clothes or bathing to irrigate a family's lawn. On a larger scale, cities can also make use of gray water systems. Elk City, Oklahoma, a member of the Southwest Oklahoma Development Authority, overhauled its sewage treatment system two years ago to achieve cost savings and promote energy efficiency.

According to Wastewater Superintendent Mike McFall, "a mechanized sewage treatment plant is really expensive to operate. Previously, when we had a mechanized plant, we had four aerators and three clarifiers. Each one had a motor that ran almost all the time. That really adds to the cost. Mechanized plants can treat a large volume of water, but the same amount has to go out that comes in. The discharge goes into the creek. When you release the water into the creek, you have to take several daily tests to make sure the water falls within state and federal standards. That gets expensive."

In contrast, Elk City now uses a series of 19 lagoons to treat its domestic sewage. McFall explains, "The flow of gravity brings the sewage to the plant. We have one lift station to pump the wastewater to the primary lagoons, but the water movement through the lagoon system is all gravity-driven from that point. To me, it's a much better system than a mechanized plant because it mimics nature. We used to spend about $2,500 each month on electricity with the mechanized plant, but now we probably spend about $1,000."

The lagoons have a 500-million gallon capacity, and with the appropriate weather patterns it can retain all the wastewater until it evaporates. However, summer rains can cause an excess level of water. The excess is drawn from the final lagoons to use for irrigating a local golf course, as well as irrigating the sewage treatment plant's lawn and alfalfa fields. In addition, one farmer has begun using the gray water to irrigate his crops, and McFall expects that more agricultural users will join the first. He says, "There was a little bit of hesitation from local farmers at first. They were worried about any odor that might come from the lagoon water. But we're pulling out the water several lagoons down the line. There is plenty of time for water to be treated, and there isn't an odor. Area residents have accepted the idea. Gray water now gets pretty heavy use throughout the summer, drawing as much as 300,000 gallons each day."

City of Elk City P.O. Box 1977 Elk City, OK 73648 Tel: 580.225.7561 Fax: 580.225.3234 http://www.elkcity.com

Southwest Oklahoma Development Authority P.O. Box 569 Burns Flat, OK 73624 Tel: 580.562.4882 Fax: 580.562.4880 http://www.swoda.org