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<br />. . <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />001992 <br /> <br />Pitt et al, August 2001. Replacing the Bypass Bow On The Colorado River <br /> <br />, augment flows to the Colorado River delta in Mexico, as long as the addition of this water to the <br />mainstem does not violate the Minute 242 salinity standard.4o . <br /> <br />Ecological Advantages of Leasing Wellton-Mohawk Water and Securing Federal Credit <br />for Yuma Mesa Groundwater <br />There are two important ecological advantages to this alternative: 1) bypass flows will be <br />replaced without creating new storage for Colorado River water and the ecological damage <br />created by reduced flood flows to the Colorado River delta would be avoided, and 2) salinity of <br />flows to the Cienega de Santa Clara will be reduced. <br /> <br />Flood flows have restored considerable native habitat in the Colorado River delta, and must be <br />protected. Minute 30641 of the International Boundary and Water Commission commits the <br />United States and Mexico to a collaborative process to identify mechanis~ to supply the delta <br />with water to sustain its ecosystems. The United States will violate the spirit of Minute 306 if <br />actions are taken to further reduce the probability of flood flows to the delta. In addition, the ' <br />United'States may be obligated not to diminish flood flows to the :delta by the Endangered <br />Species Act.42 , ' <br /> <br />Ofnote.gro~dwaterpumped from the Yuma Mesa area is slightly brackish (1400 ppm).43 BOR <br />analysis indicates that addition of pumped Yuma Mesa groundwater to the Colorado River <br />mainstem is ,likely to cause violations of the Minute 242 salinity, standard during dry winter <br />months.44 Diverting some groundwater pumped from the Yuma Mesa area would reduce the <br />probability of these violations, and would have the additional benefit of reducing the salinity of <br />flows to the Cienega de Santa Clara. Water in the MODE averages 2400 ppm; the addition of <br />25,000 acre-feet of 1400ppm water annually would reduce MODE water salinity to 2200 ppm. <br /> <br />, 2. OPERATION OF THE YUMA DESALTING PLANT <br /> <br />BOR has proposed that it could replace bypass flows by treating the bypass flow itself. or <br />another source of brackish water, at the Yuma Desalting Plant (YDp).45 The YD:r. with capacity <br />to produce 68,000 acre-feet of treated water annually, was completed in 1992 at a total cost of <br />$258 million and todal sits idle on "ready reserve" status, costing approximately $2.2 million <br />per year to maintain.4 BOR estimates YDP operational costs at approximately $21.1 million <br />annually, resulting in a cost of over $310 per acre-foot for treated water. <br /> <br />40 At such time that addition to the Colorado River mainstem of pumped Yuma Mesa groundwater would violate the <br />salinity standard, it coUld be diverted to the MODE to temporarily increase flows to the Cienega de Santa Clara. <br />41 Full Text of Minute 306 is available at http://www.ibwc.state.g:ov/lFileslMinuteslMin306.pdf. <br />42 See supra note 13. ' <br />43 U.S. Bureau of Reclamation, supra note 35. <br />44 U.S. Bureau of Reclamation, handout at Las Vegas briefing 5/8/01. <br />4S U. S. Bureau of Reclamation, handout at Las Vegas briefing 5/8/01. <br />46 Pontius, Dale, (1997) Colorado River Basin Study: Report to the Western Water Policy Review Advisory <br />Commission, p. 68. ' <br /> <br />1'1 <br />