Water Efficiency June 2012 : Page 48
IRRIGATION | PETER CANESSA, SARGE GREEN, AND DAVID ZOLDOSKE effi ciency as micro irrigation and may also be the better business decision. Section 3. In explaining the concept of recoverable and irrecoverable losses the report shows that the different water users in a basin or water use area are very often inextricably interconnected. The actions of one water user can affect others in the system. Another important finding is that diversions of water to irrigation, regardless of recoverable and irrecoverable fractions, can cause other impacts as well—to rec-reation, fisheries, natural habitats, overall water quality, and energy use. Water allocation decisions primarily pertaining to the Central Valley Proj-ect (CVP, www.usbr.gov/mp/cvp ) and the California State Water Project ( www.water. ca.gov/swp )—but also during the era when the Hetch Hetchy system for the City of San Francisco, Mokelumne Aqueduct for the East Bay, and the Owens Valley system for the City of Los Angeles were construct-ed starting over 100 years ago—were made during an era when the natural environ-ment was not as important an issue as it is now. Some of these decisions have been revisited and have resulted in major real-locations back to the environment. Th ese reallocations include: • Mono Lake Settlements of 1994-diverts 30,800 AF per year from Los Angeles supplies to the environment as Mono Lake elevation stabilizes. • Lower Owens River Settlement of 1997-further reductions in diver-sions from Owens River and ground-water pumping in the Owens Valley to Los Angeles CVPIA of 1992-800,000 AF per year from agriculture to the Sacramento and San Joaquin Valley’s environ-ment and 340,000 AF per year from agriculture to the Trinity River. Trinity River Restoration of 2000-increased the return to the river sys-tem from 340,000 AF per year under CVPIA to 647,000 AF per year in a normal water year. Biological Opinion (BiOp) regarding Delta Smelt (fi nal rules still pending) fi rst issued in December 2008 and Biological Opinion regarding Salmon Migrations (also under challenge) issued in June 2009-no fi nal estimate of total diversions from agriculture due to overlapping actions and the ef-fect of diff erent water years. National Marine fi sheries estimated a 330,000 AF per year reallocation from agricul-ture for the Salmon BiOp. San Joaquin River Restoration Program issued 2009-247,826 AF per year in a normal water year from CVP contractors to the environment. of intentional deep percolation must occur to prevent soil salinization and subsequent loss of this important productive resource. If irrigated agriculture is to survive (along with the food and fi ber it produces), soci-ety must fi nd a way to sustain an accept-able level of water quality impact. Section 4. Th e recoverable/irrecover-able concept is reintroduced to underscore that on a volumetric basis, agriculture is very effi cient. However, as was pointed out and discussed in Section 3, there are many concerns other than consumptive use. Discussion in California is shift -ing towards overall agricultural water stewardship—going beyond an argument that is grounded in the sciences (e.g., irrigation, environment, water quality) to one that is also socio-economic in nature. As with all public policy issues, the arguments can be objective (e.g., more economic benefi t can be generated from an acre-foot of water delivered to Silicon Valley than to the San Joaquin Valley) or subjective (e.g., maintaining X miles of Wild and Scenic rivers is a moral impera-tive). Further, even though there may be tangible benefi ts associated with any one argument, the body politic (i.e., voters) may favor the intangible. Th e movement towards this type of discussion is ongoing. Th e authors point to a recent paper presented to the California State Water Resources Control Board (SWRCB) by the Delta Water-master calling for a re-evaluation and possibly expanded and/or more rigorous application of the State’s constitutional imperative that water be reasonably and benefi cially used (Wilson 2011). Another indicator is California Senate Bill SBX7-7, Th e Water Conserva-tion Act of 2009. One of the mandates of SBX7-7 is that DWR, in conjunction with all stakeholders, is to “ . . . develop a methodology for quantifying the ef-fi ciency of agricultural water use” (Water Conservation Act of 2009). Th e main question, which is still to be answered as of this paper’s writing, is whether the “effi ciency” to be quantifi ed will be one based on strict volumes of water, or whether the economic benefi ts and costs of irrigation should also be considered. Th e Conclusion. Th e 2011 Update • • • • AUTHOR’S NOTE This is an expanded Executive Summary of The Center for Irrigation Technology (CIT) Staff Report “Agricultural Water Use in California: A 2011 Update.” To download the full report or for more in-formation about CIT or the Water Pro-grams at California State University, Fres-no go to: www.californiawater.org . More information is available at the US Department of the Inte-rior Bureau of Reclamation website: www.usbr.gov/mp/cvp . More information is available at the California Department of Water Re-sources website: www.water.ca.gov/swp . Water reallocations back to the environ-ment to alleviate pressures on fisheries and other natural habitats do not come without impacts. The original allocation decisions (no matter whether right or wrong) result-ed in new environments, including major investments in irrigation and municipal & industrial (M&I) facilities resulting in jobs and an increase in State Gross Product. Another major issue facing irrigation is the impact on water quality from surface runoff and deep percolation. Th e 2011 Update discusses nonpoint source pollu-tion and how agriculture must deal with its legal obligations. Irrigated agriculture now operates under new voluntary area aggregated water quality regulatory condi-tions that are contingent on continued improvement. Without this continued improvement it may well be that irrigated agriculture will have to operate under indi-vidually directed waste discharge permits in the future. However, the physics of irrigated agriculture dictate that some level 48 WATER EFFICIENCY WWW.WATEREFFICIENCY.NET
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