1F – Irrigation Water Management

Management Measure

Reduce NPS pollution of surface and ground waters caused by irrigation

  1. Operate the irrigation system so that the timing and amount of irrigation water applied match crop water needs. This requires, at a minimum, (a) the accurate measurement of soil-water depletion volume and the volume of irrigation water applied, and (b) uniform application of water.
  2. When chemigation is used, include backflow preventers for wells, minimize the harmful amounts of chemigation waters that discharge from the edge of the field, and control deep percolation. In cases where chemigation is performed with furrow irrigation systems, a tailwater management system may be needed.
  3. Don’t grow crops where irrigation is contributing to soil salinity or where soil salinity is naturally too high to support vegetation.
  4. Consider using dry-farming techniques for select crops.

Management Practices

The purpose of this management measure is to reduce NPS pollution of surface and ground waters caused by irrigation. Irrigation water should be applied in a manner that ensures efficient use and distribution of the water and minimizes runoff and soil erosion. Recommended practices include the following:

  • Determining and controlling the rate, amount, and timing of irrigation water in a planned and efficient manner. This entails knowing the daily water use of the crop, the water-holding capacity of the soil, and the lower limit of soil moisture for each crop and soil. It is also important to measure the amount of water applied to the field.
  • Controlling the manner and application of water to minimize water runoff and soil erosion. USDA NRCS-recommended irrigation systems include microirrigation, sprinklers, surface and subsurface systems, and tailwater recovery systems.
  • Designing irrigation water transport systems to eliminate as much water loss as possible.
  • Lining irrigation channels to prevent seepage to ground water.
  • Using a pipeline and apparatus to convey water to the irrigation system.
  • Using a structure that controls the rate and timing of water conveyed to the irrigation system.
  • Installing storage reservoirs to keep water for irrigation.
  • Managing the drainage water from the irrigation system to control deep percolation, to move tailwater to the reuse system, and to control erosion and adverse impacts on surface and ground waters.
  • Using filter strips to capture sediment and pollutants running off fields.
  • Use grassed waterways to capture and trap sediment entering receiving waters.
  • When irrigation water is conveyed down slopes that increase the velocity, causing erosion, install erosion controls, such as drops, chutes, buried pipelines, or erosion-resistant ditch linings.
  • When using a chemigation system, install backflow preventers on wells to minimize the harmful amounts of chemigation waters that discharge from the edge of the field and to control deep percolation. In cases where chemigation is performed with furrow irrigation systems, a tailwater management system may be needed.
  • Salt at concentrations in soil of greater than 4 millimhos/cm can alter soil structure and is toxic to vegetation. Eliminate irrigation to fields that have high salt concentrations.

Programs

  • Kings River Conservation District has an AgLine information system that provides crop water use information for the Kings River service area. Information provided for each crop includes crop water use for the past 7 days, predicted water use for the next 7 days, and total crop water use for the season to date. The numbers are updated every Friday and can be used to assist growers in irrigation management decisions. AgLine includes crop water use data for 31 cropping cases.

  • Agriculture Water Management Planning Program provides technical, financial, and administrative assistance to the Agricultural Water Management Council and to the water districts throughout the State to develop water management plans and to help implement cost-effective, efficient water management practices.

  • San Joaquin Valley Drainage Implementation Program (SJVDIP) Office of Water Use Efficiency within the Department of Water Resources. SJVDIP is an interagency program established in 1991 by a Memorandum of Understanding signed among four California State and four federal agencies. The MOU created a partnership among agencies to help implement recommendations of the San Joaquin Valley Drainage Program published as the Rainbow Report in 1990. The SJVDIP then developed a new Drainage Management Strategy in 2000 to implement the updated recommendations. SJVDIP's role was recently expanded to cooperate with another State and federal program, CALFED. The expanded SJVDIP is known as Statewide Drainage Management Program/ SJVDIP.

  • Department of Water Resources, California Irrigation Management Information System (CIMIS) helps agricultural growers and turf managers who administer parks, golf courses, and other landscapes to develop water budgets for determining when to irrigate and how much water to apply.

  • RWQCB Central Coast, Conditional Waiver Program for Irrigated Agriculture adopted in July 2004. The intent of this Conditional Waiver is to regulate discharges from irrigated lands to ensure that such discharges are not causing or contributing to exceedances of any Regional, State, or Federal numeric or narrative water quality standard. Irrigated lands are lands where water is applied for producing commercial crops and, for the purpose of this program, include, but are not limited to, land planted to row, vineyard, field, and tree crops, as well as commercial nurseries, nursery stock production, and greenhouse operations with soil floors that are not currently operating under WDRs.

  • RWQCB Central Valley, Conditional Waiver Program for Irrigated Agriculture adopted in July 2003. Under the Conditional Waiver Program, growers with irrigated lands that discharge waste that can degrade surface water quality must now select one of three options to obtain regulatory coverage under the Water Code. Those affected include growers (owners/operators) of irrigated lands; managers of wetlands; and local districts that discharge tailwater, water from underground drains, water from operational spills, and storm water runoff to surface waters.

  • Westland Water District’s Water Conservation Cost-Share Programs continues to offer the Expanded Irrigation System Improvement Program (EISIP) to district water users and landowners. This program offers low interest rates to water users for the lease-purchase of irrigation system equipment funded by State Revolving Fund loans. The EISIP offers the opportunity to lease portable aluminum irrigation equipment and other improved irrigation systems, including microirrigation, linear move and center pivots, and tailwater reuse systems. The Agricultural Pumping Efficiency Program is available for all agricultural electric and natural gas utility accounts that are used for pumping water and paying the Public Goods Charge.

  • University of California, Davis, Cooperative Extension Service, Irrigation Management this program is dedicated to the study of irrigation problems and techniques. The Cooperative Extension Service develops and extends research based information that promotes environmentally sound agricultural practices and that improves the efficient utilization of California’s valuable water resource.

  • The Pacific Northwest Cooperative Agricultural Weather Network, Hydromet network is a series of automated data collection platforms that provide information necessary for near-real-time management of Reclamation's water operations in the Pacific Northwest. As a subset of the overall Hydromet network, this agricultural network, dedicated to crop water use modeling and other agricultural applications, has been identified as AgriMet.

Information Resources

  • Water Conservation Field Services Program, Demonstration of Innovative Technologies programs are supporting local demonstration of projects such as improved water measurement, use of automation and telemetry control, approaches to minimizing canal and ditch seepage, and on-farm irrigation management methods. Activities include (1) assist with research, evaluation, and demonstration; (2) sponsoring conservation demonstration projects and activities; and (3) coordinating financial assistance for joint projects and partnerships with other agencies.

  • The U.S. Bureau of Reclamation’s National Irrigation Water Quality Program (NIWQP) is an intra-departmental program that evaluates Department of the Interior irrigation projects, considers drainwater contamination and related impacts on endangered species and migratory birds, assesses legal responsibilities associated with environmental laws, and develops and implements alternatives for remediation.
  • The U.S. Bureau of Reclamation’s Managing Water on the Farm provides basic information on three types of irrigation systems: gravity flow surface irrigation, pressurized sprinkler irrigation, and low-pressure micro irrigation.

  • Center for Irrigation Technology at California State University at Fresno, WATERIGHT was developed with significant support from the U.S. Bureau of Reclamation and is designed to be a multifunction, educational resource for irrigation water management. The site is designed for three audiences: homeowners, commercial turf growers, and farmers.

  • USDA NRCS Irrigation Page provides links to water management models, irrigation components, facts, handbooks and manuals, training, and information sites.

  • University of California Cooperative Extension Service Water Management Series Publications are available for purchase from the Cooperative Extension Service for $15 to $25. Titles include: Agricultural Salinity and Drainage, Drip Irrigation for Row Crops, Irrigation Pumping Plants, Microirrigation of Trees and Vines, Scheduling Irrigations: When and How Much Water to Apply, Surface Irrigation, and Surge Irrigation.

  • U.S. Bureau of Reclamation’s A Guidebook for Preparing Agricultural Water Conservation Plans: Achieving Effective Water Management is designed to help agricultural water districts and irrigation organizations prepare water conservation and management plans to achieve more efficient water use. The Guidebook is aimed at organizations of all sizes and complexities, both Federally-supplied and private.

  • California Farm Water Coalition, The Water Fact Book: California Agriculture and Its Use of Water is a 40-page comprehensive guide to agriculture's use of water, featuring how much water is available for use in our state and how it is used on the farm. A unique look at how water flows through California's State Water Project and the costs associated with transportation is presented.

  • The Pacific Northwest Cooperative Agricultural Weather Network, AgriMet Irrigation Guide is an informational guide that provides irrigation management practices for crop production for California.

References

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