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Pipeline to curb Tempe lake algae A pool of water east of Tempe Town Lake is prompting the city to build a $2.5 million pipe and pump system. Tempe needs to get rid of the water to regain control of the lake's algae and pH content and make it safe for swimming in time for the spring triathlon season. More than a thousand people are scheduled to swim in Town Lake in the Ford Ironman Arizona Triathlon on April 15. Athletes also are scheduled to use the water dozens of times during subsequent weekends for other races. In the past, bad water hampered two swimming events. One was canceled and the other was moved to a pool on the Arizona State University campus. Tempe's leaders consider the pipeline a key move to maintaining an attraction that has generated millions of dollars. Last year's Ford Ironman had an estimated $4.5 million economic impact on the city, according to the Tempe Convention and Visitors Bureau. Town Lake has been a triathlon site since 2001. In recent weeks, the amount of algae in Tempe Town Lake has decreased because of cold, cloudy weather. Sunlight fosters algae growth. But otherwise, algae has become a constant problem. The lake's keepers have had thousands of gallons of copper-based algaecide dumped into the lake to rid it of the pesky plant. The algaecide, which isn't toxic to animals or people, is sprayed onto the water's surface throughout the lake or in spot-treatments, according to Basil Boyd, the city's Water Resources hydrologist. In past years, the city used water from the Salt River Project or well water to keep the lake full. Then, the water was treated three or four times a year for algae. But all that changed in 2005 when snowmelt from Arizona's mountains flowed south and filled the Salt River. Add to that water from Mesa's water-reclamation plant and Mesa's storm drains, plus water from gravel quarries east of Tempe. This water now continuously flows over Town Lake's eastern dam and mixes with lake water. While it's flowing, algae grows in it. The presence of algae increases water's pH level, a measurement of acid and alkaline levels of a liquid. Water with high pH can cause eye and skin irritation and infections in open wounds, according to county health officials. Up to a dozen algaecide treatments a year are required to keep the water's pH level low, Boyd said. Each treatment costs about $10,000 for chemicals and labor. |