Irrigation Strategies for Erosion Reduction in the Salton Sea Watershed

The Issue

The two rivers that drain California's Imperial Valley, the Alamo River and the New River, as well as the Salton Sea are listed on the state’s 303(d) impaired water list. Total Maximum Daily Load (TMDL) standards for sediment and silt have already been developed for Imperial Valley drains and rivers. The TMDL goal is to reduce the current load of sediment and silt in drainage water by 50 percent. Growers are required to comply with TMDL standards to reduce the concentration of sediment and silt in drainage waters of the Imperial Valley.

What Has ANR Done?

UCCE Imperial County advisors along with specialists and professors from UC Davis and UC Riverside developed and implemented research and outreach projects to address water quality problems in the Salton Sea watershed. UC researchers evaluated the efficacy of three irrigation management practices and measures that growers could use to improve water quality and reduce sediment load to comply with the Federal Clean Water Act: (1) runoff reduction, (2) surge irrigation and (3) application of polyacrylamide (PAM) to reduce erosion. Among other findings, we determined that implementing the above management measures could reduce soil erosion by as much as 95 percent and reduce the load of phosphorus in surface runoff water by 50 percent.

We conducted educational and outreach efforts to promote these practices that conserve water and improve water quality, including 10 educational seminars, field days and workshops in the Imperial Valley.

UCCE Advisors Khalid Bali and Juan Guerrero served on the California Regional Water Quality Control Board Technical Advisory Committees for the two TMDLs that were developed in the Salton Sea watershed.

Information about the educational activities are also available on the water quality Web site, http://tmdl.ucdavis.edu

The Payoff

Irrigation management saves water and improves water quality

Recommendations based on our research for improving water quality were included in the final state and federal silt and sediment TMDL standards. Our management practices are used by the California Regional Water Quality Control Board-Region 7 to promote changes in irrigation practices to improve water quality in the region.

One of the management practices that we have exclusively developed at the UC Desert Research and Extension Center is used in the valley to conserve water and improve water quality. Implementation of this practice on commercial farms increases water use efficiency by more than 12 percent and reduces the load of sediment and soluble phosphorus in drainage water by more than 50 percent.

Contact

Supporting Unit:

Imperial County
 
Khaled M. Bali, Irrigation/Water Management Advisor, UCCE Imperial County, 1050 E. Holton Rd., Holtville, CA 92250.
(760) 352-9474 Email: kmbali@ucdavis.edu