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Imperial Irrigation District efficiency conservation definite plan: on-farm conservation opportunities and costs

Date

2008-05

Authors

Clark, Byron, author
Eckhardt, John R., author
Keller, Jack, author
Davids, Jack, author
U.S. Committee on Irrigation and Drainage, publisher

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Abstract

Water use in the West is changing, and nowhere is that being felt more acutely than in the Imperial Irrigation District (IID), a 450,000-acre district in Southern California where longstanding agricultural water users are under intense pressure to transfer water to the region’s ever-thirsty and ever-expanding urban areas. Four years ago, the District agreed to launch a massive conservation program that would free up roughly 10 percent of its water for transfer to San Diego and others. The heart of the agreement called for IID to generate more than 300,000 acre-feet annually through a combination of District and voluntary on-farm efficiency conservation savings. In 2007, IID completed their Efficiency Conservation Definite Plan (Definite Plan) that outlined strategies for both delivery system and on-farm water savings. This paper, one of seven in this conference detailing the findings of the Definite Plan, addresses on-farm conservation. On-farm conservation opportunities were evaluated by defining conservation families, which are made up of individual seasons for unique fields with similar crops, soils, and irrigation methods. Members of each conservation family are expected to respond similarly when incentives for conservation are offered. Sets of applicable conservation measures were identified for each conservation family. Incremental costs of implementing conservation measures were estimated for each field and crop season uniquely. The change in water deliveries resulting from implementation of each applicable conservation measure for each field and crop season was estimated based on the characteristics of the measure and the historical potentially conservable water. The resulting set of applicable conservation measures, projected costs, and estimated water savings for each field and season were used to simulate grower responses to a variety of incentive offerings under a voluntary conservation program. Over 100,000 unique field-seasons from the 1998 to 2005 water years were evaluated. Typical net implementation costs ranged from $35 per acre per year for management based conservation measures to more than $800 per acre per year for capital-intensive conservation measures with pressurized irrigation. Typical savings ranged from zero acre-feet per acre per year for field-seasons with historically high performance to more than 1.5 acre-feet per acre per year for capital-intensive conservation measures on fields with historically low performance. The substantial variability in implementation costs and water savings among field-seasons results in a wide range of implementation costs per acre-foot conserved, which has important implications on the design of incentives for on-farm conservation.

Description

Presented at Urbanization of irrigated land and water transfers: a USCID water management conference on May 28-31, 2008 in Scottsdale, Arizona.

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