Department of Water Resources Home

Agricultural Water Use

urbanwatersystemAgricultural Water Use

California's unique geography and Mediterranean climate have allowed the State to become one of the most productive agricultural regions in the world. The Sierra Nevada Mountain range that lines the eastern edge of the State capture and store winter precipitation that can be then used for summer irrigation in the Central Valley. This water, combined with the Mediterranean climate permits the growing of a great number of crops. California produces over 250 different crops and leads the nation in production of 75 commodities. California is the sole producer of 12 different commodities including almonds, artichokes, dates, figs, raisins, kiwifruit, olives, persimmons, pistachios, prunes and walnuts.

Most of this production would not be possible without irrigation. In average year California agriculture irrigates 9.6 million acres using roughly 34 million acre-feet of water of the 43 million acre-feet diverted from surface waters or pumped from groundwater.

California's population growth and greater awareness of environmental water requirements has increased the pressure on California agriculture to use water more efficiently and to make more water available for urban and environmental uses. Decreasing agricultural water use is difficult for several reasons. First, California agricultural water use when considered on a broad regional scale, for the most part, is very efficient. Individual fields and farms in some regions may have low efficiencies, but water that is not used on one farm or field is often used on a nearby farm or field. Secondly, for most crops, production and yield is directly related to crop water use. A decrease in applied water will often directly decrease yield. The key is management strategies that improve water use efficiency without decreasing yield.

There are technologies and management strategies available that conserve water while maintaining yield and production standards. These technologies and management strategies like improved irrigation scheduling and crop specific irrigation management often not only conserve water, but also save energy and decrease grower's costs.

Below is a list of commonly used agricultural water conservation methods for both on-farm and district level implementation.

On Farm Water Conservation Methods

Irrigation Scheduling
Deciding when and how much water to apply to a field has a significant impact on the total amount of water used by the crop water use efficiency and irrigation efficiency. A number of different scheduling systems have been developed that can use either soil- plant or atmosphere-based measurements to determine when to irrigate. Using a more scientific approach to scheduling has generally been shown to decrease the amount of water applied while improving yield.

Tailwater Return Systems
To provide adequate water to the low end of the field, surface irrigation requires that a certain amount of water be spilled or drained off as tailwater. Tailwater return systems catch this runoff and pump the water back to the top of the field for reuse.

Irrigation System Improvements
Irrigation system improvement involves modifying the irrigation method or use of hardware and software to properly apply water to the field while minimizing water losses. For example improved furrows, combination of furrow and sprinkler, and changing from surface irrigation (flood, furrow and border check) to pressurized systems. Changing from surface irrigation to pressurized systems (sprinkler, drip, microirrigation) generally increases irrigation distribution uniformity and decreases applied water, although with certain soil types and applications, surface irrigation can be very efficient. In California there has been a trend to shift from surface irrigation to pressurized systems.

Irrigation District System Improvements

Canal Lining
Lining canals with high seepage rates can result in significant water savings. This is especially important where the groundwater is saline and the water cannot be reused without desalination.

Canal Structure Improvements
Replacing or improving canal structures can improve an irrigation district's ability to manage and control water in the district and reducing spillage.

Remote Monitoring and Control
Many irrigation districts are installing remote monitoring and in some cases remote control systems such as Supervisory Control and Data Acquisition Systems (SCADA). Remote control systems allow district to measure flow or water depth and allows the district to remotely operate hydraulic structures or devices. Remote monitoring and control systems allow districts to improve water management and control.