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LOW-LEVEL EMERGING CONTAMINANTS IN LAKE HAVASU, ARIZONA AND CALIFORNIA AND THEIR ACCESS TO LAKE HAVASU CITY'S DRINKING WATER SUPPLY
Citation:
Wilson, D. C. AND T. L. JONES-LEPP. LOW-LEVEL EMERGING CONTAMINANTS IN LAKE HAVASU, ARIZONA AND CALIFORNIA AND THEIR ACCESS TO LAKE HAVASU CITY'S DRINKING WATER SUPPLY. Presented at Lake Mead Science Symposium, Las Vegas, NV, January 13 - 14, 2009.
Impact/Purpose:
Presentation
Description:
In preparation of a wastewater effluent re-charge and recovery program, involving alluvial fan sediments, the City of Lake Havasu initiated a survey to evaluate possible waterborne sources of emerging contaminants in the water/wastewater distribution cycle. This distribution cycle includes Lake Havasu water (raw and treated well water), treated wastewater, and ambient groundwater where effluent injection and subsequent groundwater withdrawals will take place. The results from Lake Havasu (raw and treated) water analyses are discussed here. Grab samples were taken once a quarter over a year and were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS) at Southern Nevada Water Authority’s (SNWA) River Mountain Research facility and at the U.S. Environmental Protection Agency’s (EPA) Las Vegas National Exposure Research laboratory (NERL). Several pharmaceutical compounds (atenolol, caffeine, carbamazepine, dilantin, meprobamate, primidone, and sulfamethoxazole), the herbicide atrazine, and the insect repellant DEET, have been consistently present in ultra-low concentrations (ng/L range) in the Colorado River, above the urbanized areas of Lake Havasu, and in Lake Havasu’s Thompson Bay adjacent to Lake Havasu City. Further, the concentrations of these compounds at each of the two locations are comparable, and vary little seasonally. Several other compounds analyzed such as MDMA and TCEP, are more episodic. Raw source well water, which has filtered through at least 80 feet of subsurface gravels and sands below the lake bottom, contains six of the above compounds, of which, sulfamethoxazole is apparently extracted during the city’s biological manganese removal, potable water treatment process. Concentrations of the other five constituents in the finished treated water are a largely unchanged.