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<br />REPLACING THE BYPASS FLOW ON THE COLORADO RIVER: <br />ECONOMIC AND ENVIRONMENTAL CONSIDERATIONS <br /> <br />Jennifer Pitt', Chris W. Fitzer', Lisa Force" <br /> <br />EXECUTIVE SUMMARY <br /> <br />The federal government may, at some future date, be obligated to replace water that is removed <br />from the Colorado River via the Main Outlet Drain Extension (the "bypass flow") and diverted <br />into the Cil!nega de Santa Clara, a large, open-water wetland in Mexico. The Colorado River <br />Basin Salinity Control Act establishes replacement of the bypass flow as a federal obligation. <br />Originally diverted to ensure that Colorado River water deliveries to Mexico satisfy 1972 <br />salinity standards amending the 1944 Rivers Treaty, the bypass flow sustains an important <br />habitat in the Colorado River delta. The Cienega de Santa Clara is home to thousands of <br />migratory and resident waterfowl, as well as the Yuma clapper rail and the desert pupfish, both <br />endangered species. <br /> <br />At present the bypass flow is replaced by water conserved with the lining of the Coachella canal. <br />At such time that the federal government cart no longer take credit for this conserved water, it <br />must secure a new source. Finding "new" water in the Colorado River poses significant <br />problems as the river is overallocated and its ecosystems are already under stress. This paper <br />examines several alternatives, and identifies a lease of water from the Wellton-Mohawk <br />Irrigation and Drainage District as the least ecologically damaging way for the federal <br />government to fulfil its obligation to replace the bypass flow. Not only would this solution <br />minimize hann to the Cienega de Santa Clara and the Colorado River delta, it is less expensive <br />than other alternatives currently under consideration by the Bureau of Reclamation. <br /> <br />BACKGROUND <br /> <br />Salt In the Colorado River <br />On its journey from the peaks of the Rocky Mountains to the Gulf of California, the Colorado <br />River accumulates 9 million tons of salt annually.' Natural sources contribute about half of the <br />salt in the river, but some 37% is the result of irrirated agriculture, which returns to the river <br />additional salt along with agricultural wastewater. The amendment. of the 1944 U.S.-Mexico <br />Rivers Treaty' with the adoption of Minute 2424 of the International Boundary and Water <br /> <br />. Environmenlal Defense, 2334 N. Broadway, Boulder, CO 80304 <br />.. Living Rivers, P,O, Box 1589, Scollsdale, AZ 85252 <br />I TaylorO. MilIeret aI., (1986). The Salty Colorado. xiii <br />2 Id,p. 5. <br />, Treaty wilh Mexico Respecting Ihe Utilization ofthe Waters of Ihe Colorado and Tijuana Rivers and ofthe Rio <br />Grande, Feb. 3,1944, U,S,-Mex, Stat. 1219, 1265. <br />4 Full text of Minute 242 can be found allhe International Boundary and Water Commission website: <br /><htto:/Iwww.ibwc.slale.eov/FORAFFAI/MINUTES/minindex.HTM>. <br /> <br />1 <br />