WATER CONSERVATION
Overview District Conservation Programs and Publications Efficiency Water Meters Groundwater Management Irrigation Techniques Irrigation System Management Program
Overview
Westlands Water District has a limited surface water supply, therefore, water conservation techniques are practiced every day by west side farmers. Since 1991, the Bureau of Reclamation has dramatically reduced the amount of water it delivers to Westlands, to the point where today, the District can expect to receive only about 50 percent of its contractual water supply in an average water year. But even with a full CVP entitlement, Westlands farmers would not have all of the water needed to produce crops on all of the available land. As a result, the farmers on the west side have become experts at maximizing irrigation efficiency. Westlands’ farmers rely on advanced irrigation technology and management to more efficiently use their water allocation. Ultimately, consumers are the ones who benefit from a farmer’s use of water, since it generates food and fiber products, jobs and economic activity for our region, state and nation.
District Conservation Programs and Publications
Districts under contract for federal water are required to develop and maintain a water conservation plan. However, water conservation is not a new focus for Westlands. For many years, the District has worked to educate its water users, through the use of programs, publications and workshops. Westlands implemented its first water conservation program in 1972. This original program, known as the Irrigation Management Services Program, was intended to provide farmers with crop water use information and up-to-date information on irrigation techniques and systems. In 1978, the program was replaced with the District’s current Irrigation Guide, which provides Westlands farmers with crop water use information on a weekly basis. The guide helps farmers estimate the crop water use in their particular area, enabling them to effectively schedule the amount and timing of crop irrigations. Today, area-specific versions of the guide are printed for the three regions in the District, reflecting various micro-climates. Westlands also maintains an Irrigation Management Handbook, a resource that provides information about specific conditions in the District, including soil and crop characteristics, irrigation scheduling, water use planning and more. The District’s water conservation program evolved into what is now the Irrigation System Improvement Program, a program that provides financial assistance to farmers. Since the program began, it has promoted several water conservation ideas and activities, many of which are widely used today. The program has been approved by the State Water Resources Control Board and provides low-interest loans to purchase sprinklers, micro-irrigation, linear-move or center-pivots and/or tailwater reuse systems. The lease/purchase arrangement extends over four years. The loans encourage farmers to try new irrigation techniques, while the District and State help off-set the cost of capital.
Efficiency
Westlands’ farmers continue to have one of the highest seasonal application efficiency ratings in the nation, with a 20-year average of 83 percent. The District is committed to further improve this rating; however, there are factors that limit projected on-farm efficiency. One such factor is the distribution of water. Since it is nearly impossible to apply all available water to the field at one time, the result is often a lack of distribution uniformity – irrigation water distributed to different areas in the field moving through the root zone at different rates. District farmers utilize many different irrigation techniques to address this issue and improve uniformity of irrigations.
Water Meters
Water meters are required at each District delivery and on private wells participating in any of the District’s conjunctive use programs. The meters provide accurate data that help water managers allocate limited supplies and recoup true delivery costs. In addition, farmers can calculate their irrigation efficiency by knowing the precise amount of water delivered. To ensure accuracy, all meters are placed on a preventive maintenance cycle ensuring each meter is calibrated and tested every three-to-four years. Accurate metering allows the District and its farmers to carefully manage and account for all water delivered.
Groundwater Management
The Deep Groundwater Conditions Report is prepared annually to monitor both the quantity and quality of groundwater resources within the District. Groundwater measurement and quality testing have proven useful to individual farmers to help them better manage water supplies, facilitate more accurate irrigation scheduling, monitor pump efficiency, and participate in District groundwater programs. Such measurement and testing also enables the District to better monitor groundwater supplies, calculate drought effects and determine water needs.
Irrigation Techniques
Westlands’ farmers have modified their irrigation programs to maximize the limited supplies, recognizing that a diversified crop mix depends on equally-as-diversified and flexible irrigation systems. Farmers continue to use irrigation systems with higher efficiency, as shown in the following table. Table 1: On-Farm Irrigation Systems PERCENT OF LANDS IRRIGATED TYPE OF SYSTEM 1985 1990 1995 2000 2004 Surface Furrow 60 38 34 28 23 Surface Border Strip 3 5 2 2 2 Combination Sprinkler/Furrow 15 38 43 43 39 Pressurized Sprinkler 21 16 15 14 11 Pressurized Drip/Trickle 1 3 6 13 25 The popularity of the combination of sprinkler and furrow systems can be attributed to the practice of pre-plant irrigation, commonly called pre-irrigation. The central San Joaquin Valley does not get enough rainfall to provide farmers with all of the water needed for pre-irrigation. Therefore, during the winter, some of the farmers in the District begin to pre-irrigate the land. Using a sprinkler system can be an efficient technique, allowing farmers to apply water to the fields before they begin to plant. The goal is to fill the soil profile with water as far down as the plant roots are expected to grow. Pre-irrigation helps to ensure the plants will have enough water to sustain growth during the hot summer months. Once the plants have been established, farmers will switch to a well-managed furrow irrigation program, depending on the type of crop and the stage of its development.