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<br />uJJ5J2 <br /> <br />Executive Summary of Critical Issues <br />Topic - Colorado River Water Quality <br /> <br />Last Updated <br />February 1, 2005 <br /> <br />CAP Position <br />The water quality in the Lower Colorado River is quite good. The river and <br />lakes are used for full body contact recreation, fishing, and riparian habitat. <br />The water is used to irrigate over 1.0 million acres of cropland and is treated <br />for use as municipal and domestic water supply for over 25 million people. <br /> <br />Summary of Issue: <br />Recently, there were news reports about the American Rivers announcement of <br />the Colorado River as the Nation's most endangered river due to water quality <br />problems concerning perchlorate, nitrates, and a uranium mine tailings pile <br />near Moab, UT. Management of salinity in the river is an ongoing program. All <br />of these issues are well known and are being addressed. None are a significant <br />problem. <br />· Perchlorate enters the Colorado River from only one source, old <br />industrial development sites along the Las Vegas Wash that flows into <br />Lake Mead near Henderson, NY. Site cleanup is well underway and is <br />steadily reducing the perchlorate levels in the Colorado River. Current <br />levels are less than 4 ppb below Hoover Dam. The National Academy of <br />Sciences recently recommended that the EPA consider setting its federal <br />water quality standard for percWorate at 20 ppb. <br />· Nitrates exist at certain locations in the Lower Colorado River from <br />agricultural return flows and from localized concentrations of septic <br />tank/leach field inf1ltration into the river. There are no significant Ag <br />return flows upstream of the CAP diversion. There are no general area <br />problems from leach fields. Local problems are being addressed by <br />installing sewer systems and other official programs arising from local <br />health concems. <br />· The Moab tailings pile has been addressed and federal officials are <br />determining the best fix. In the interim, it is located outside the <br />normal flood plain and is not contributing to any water quality <br />problems in Lake Powell, Lake Mead, or the Lower Colorado River. <br />· The salinity level (total dissolved solids) is less than 700 ppm of TDS <br />at the CAP diversion. The Basin states and the U.S. have an ongoing <br />Salinity Control Program in which CAP is actively involved. There are <br />no significant issues. The salinity levels are lower today than 30 <br />years ago. The drought and lower reservoir levels are causing some <br />rise in current levels. <br /> <br />G: \ data \gm \micetic \ Critical Issues \ Executive Summaries \ Colorado River Water Quality. doc <br />