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Operation of state water project impacts agriculture

The Issue

Rice production in California is situated in the heart of the state’s largest watershed. The production area is flanked to the south by a rapidly expanding urban area and co-occupies an area with the few remaining native salmon fisheries in the state. Consequently, water resource management decisions must consider the needs of urban users, wildlife habitat and agricultural production. An important factor is water temperature. Species of fish protected under the U.S. Endangered Species Act require cold water temperatures in a time frame that coincides with the the rice-growing season and rice growth is inhibited by cold water. Understanding the implications of water management decisions on agricultural systems is one challenge in addressing the needs of all stakeholders.

What Has ANR Done?

A UCCE farm advisor conducted a series of controlled field experiments to quantify the effects of low water temperature on rice productivity. In addition the advisor determined the associated region-wide impact on area rice yields and documented the seasonal water temperature profiles throughout the area's irrigation network during rice growing season. The impacts of cold water on rice production were a critical issue in the federal relicensing of the Hyatt and Thermalito Powerhouses, important features of the Oroville Reservoir Complex. Results from this UCCE study were presented to the Federal Energy Regulatory Agency, the California Department of Water Resources, the Metropolitan Water District, the State Water Contractors, the Northern California Water Association, the County Boards of Supervisors, and numerous citizens’ groups.

The Payoff

UC research pivotal in successful settlement negotiation

In 2008, five irrigation districts and the DWR executed a settlement agreement titled "Amendment to Agreements on Diversion of Water from the Feather River and Settlement of Issues Related to the Temperature of Water Diversions." The agreement resolves a 40-year-old issue by remediating the yield losses in rice due to low temperature water. The economic impact on the local farm economy is estimated at over $75 million over the duration the renewed license.

Clientele Testimonial

Dr. Mutters’ thorough analysis and technical expertise earned him the respect of professionals and regulators on all sides of the issue. - Ted Trimble, Western Canal Water District


Randall Mutters,rgmutters@ucdavis.edu,(530) 538-7200