suburb of Goodyear, which receives most of its water from CAP, plans by 2016 to inject 133,000 acre-feet of treated wastewater into the ground for the next 20 years to solidify its water supply. Statewide, Arizona is looking at op- tions such as revised forest management
practices and desalination of brackish groundwater to augment water supplies. According to CAP, it is providing incen- tives to nine irrigation districts in central Arizona to reduce their use of Colorado River water in 2015 and 2016. • – Gary Pitzer
“published records, satellite images and direct observations indicate that surface water from the Colorado River had not reached the sea since at least 2000.” Most of the pulse flow “infiltrated
Pulse Flows, Possible Desalination Plant Highlight Minute 319 Implementation
More than two years after officials
agreed on a binational Colorado River agreement, steps are being taken to implement its provisions that strengthen ties between the United States and Mexico. Known as Minute 319 to the 1944
treaty between the two countries, the agreement includes provisions for surplus and shortage sharing, an Intentionally Created Mexican Allocation (and associ- ated exchange with U.S. water users), salinity management, water for the envi- ronment and international infrastructure projects. Part of the agreement, which is in effect until Dec. 31, 2017, is a pilot pro- gram to create 158,088 acre-feet of base flow and pulse flow for the Limitrophe, the border between the United States and
Mexico, and the Colorado River Delta. More than 100,000 acre-feet of water
flowed down the river and into the Delta between March 23 and May 18, 2014, spreading over more than 4,000 acres of river channel and floodplain as it sunk into aquifers and dispersed and germi- nated seeds for cottonwood and willow trees. “We were successful in delivering
environmental water to key areas,” said Edward Drusina, U.S. commissioner of the International Boundary and Water Commission (IBWC), in a statement. “I look forward to hearing from our team of scientists as they continue to study the pulse flow’s impact on our habitat restoration efforts.” An initial progress report released Dec. 4, 2014 by the IBWC noted that
to groundwater, transpired from plants, evaporated from soil and water surfaces, or was retained in soil and topographic depressions,” the report said. A “signifi- cant portion” of the water infiltrated into the aquifer beneath the Limitrophe and the dry section south of San Luis Rio Colorado. “More than 90 percent” of the water did not flow farther than river mile 37, which is 16 miles downstream of the Southerly International Boundary. A mid-term report on the pulse flow is expected in 2016 and the final compre- hensive report is expected in 2018. Meanwhile, Mexico, the IBWC and water agencies in the United States are looking to implement another provision of Minute 319 – a possible 50 million gallon-per-day seawater desalination plant in Rosarito Beach, Mexico, a proj- ect that would create a new source of water. “We know that a plant can be built,”
Dan Denham, the San Diego County Water Authority’s Colorado River program manager, told the San Diego U-T San Diego in August. “Te question is, what size the plant will be, is it going to meet just Mexican demands or broader U.S. demands and how is the water going to get across the border?” Roberto Espinosa, Tijuana representa-
tive of Mexico’s Comision International de Limites y Aguas, told the U-T San Diego that the project requires an analysis of costs and financing options, environ- mental impacts and where the produced water would be delivered. If built with U.S. money, water
produced by the plant could be used in Mexico on an exchange basis, meaning Mexico would agree to lease some of its allocation of Colorado River water to agencies such as the San Diego County Water Authority. • – Gary Pitzer
Winter 2014-2015 • River Report • Colorado River Project • 11
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