By: Fritz Durst
Recently, the California Rice Commission released the Environmental Sustainability Report, highlighting the efforts rice growers are undertaking to enhance land use benefits and protect the environment. Included in the report is an analysis of water use by ricelands over the past 30 years. This historical analysis provides an excellent example of increasing and sustained efficient water management for the industry. In the 1980s, average per-acre water application for rice was approaching 6 acre-feet. By the mid-1990s, that number had dropped to below 5 acre-feet per acre and for the past decade, average water application is 4.1 acre-feet per acre.
This did not occur by accident. Over the past several decades, the rice industry and irrigation districts have worked together to increase efficiency both at the farm and district levels. The laser leveling of rice fields, now the industry standard, allows farmers to use less water to grow rice. Farmers also invested millions of dollars to advance research to develop short stature rice varieties that use less water.
Irrigation districts that deliver water to rice lands have also worked to increase efficiency. The engineering of the irrigation districts where rice is grown allows water to be reused multiple times, moving from field to field, into drains where it is pumped to be used again, and, in some cases into what is called a tailwater recovery system, where the water is pumped once more from the bottom of the irrigation system to be run through the system all over again. When water reaches the end of an irrigation system in the Sacramento Valley, it is either picked up and utilized by another district, delivered to a Federal Wildlife Refuge or State Wildlife Area or flows back to a river or stream where it can be utilized by others downstream.
These water management practices have allowed a limited number of surface water diversions to supply vast acreages of irrigated farmland, managed wetlands as well as National Wildlife Refuges and State Wildlife Areas as water is pumped out of drains and reused numerous times to supply multiple beneficial uses on a regional level before returning to the river. In a “recoverable loss” system (where water not consumed by crops or used to recharge groundwater basins returns to the system and is available for other uses) like the Sacramento Valley, this is also why it is important to evaluate efficiency at a regional level. Measuring water and evaluating efficiency at the field level does not provide the comprehensive assessment that is necessary, because the water is reused multiple times. In the Sacramento Valley, professional water managers have established the framework for this comprehensive assessment. In July 2011, “Efficient Water Management for Regional Sustainability in the Sacramento Valley” was released.
Ricelands are a valuable part of the habitat that contributes to the rich mosaic of land uses in the Sacramento Valley. Rice farmers have made considerable strides over the past couple of decades to increase on-farm efficient water management. Water managers who operate the irrigation systems that provide water to the rice lands have also implemented programs to further increase efficiency and to incentivize farmers and districts to work together to maximize the beneficial uses the water provides. These efforts are part of a continuous program to enhance efficiency in the Sacramento Valley. In the future, more can and will be done to sustainably manage the water resources in the Valley to provide water for environmental, agricultural and urban uses.
