About the District
Semitropic Water Storage District is California’s largest water storage district and home to the state’s largest groundwater banking program. Located in Kern County, the District was established to provide a reliable water supply for one of the most productive agricultural regions in the world. Today, Semitropic continues to support the long-term success of California agriculture while serving as a critical component of California’s statewide water infrastructure.
The District delivers imported State Water Project supplies, manages groundwater resources, and operates one of California’s most successful local conjunctive use programs by capturing water during wet years, storing it safely underground, and recovering it during droughts and other water supply shortages. This integrated approach improves the reliability of water supplies for local farmers, supports sustainable groundwater management, and increases flexibility to respond to California’s highly variable hydrology.
Strengthening Water Reliability Across California
The Semitropic Groundwater Banking Project provides 1.6 million acre-feet of underground storage capacity, benefiting both agricultural and municipal water users throughout California. By maximizing the recharge of available water during wet periods and preserving those supplies for future needs, the District strengthens drought resilience and improves the water supply reliability for millions of Californias from the Bay Area to Southern California.
1.65 Million
Acre-Feet
Underground storage capacity
Millions of Californians
Supported through
statewide water partnerships.
Our History
Semitropic Water Storage District was formed in 1958 by local landowners to develop a dependable water supply for agriculture in Kern County. Before imported water became available, farming in the region relied almost entirely on groundwater pumping, resulting in declining groundwater levels and increasing concerns over long-term water supply reliability.
Construction of the California State Water Project and completion of the California Aqueduct transformed the region by providing access to imported surface water. Semitropic developed an extensive distribution system to deliver this water to agricultural users while reducing dependence on groundwater, successfully allowing the local aquifer to recover.
Recognizing that California’s water supplies fluctuate dramatically between wet and dry years, Semitropic became a pioneer in groundwater banking during the late 1980s and early 1990s with the development of the Semitropic Groundwater Banking Program (Semitropic Groundwater Bank). The District partnered with the State of California and urban water agencies to develop an innovative program that captures surplus water during wet years, stores it underground, and recovers it during future droughts or other dry conditions. These early banking projects demonstrated the value of managed aquifer recharge and established Semitropic as a leader in large scale groundwater banking operations.
Beginning in the early 2000s, declining reliability of the State Water Project (SWP), driven by prolonged droughts, increasing environmental restrictions, and changing Delta operations, presented renewed challenges to the District’s water supply. Reduced and increasingly unpredictable deliveries of imported surface water forced greater reliance on groundwater pumping to meet agricultural demands, reversing earlier improvements in groundwater conditions and contributing to declining groundwater levels. These challenges reinforced the importance of developing more resilient water supplies, expanding groundwater recharge opportunities, and strengthening the District’s ability to manage available surface water and groundwater to sustain local agriculture.
The passage of California’s Sustainable Groundwater Management Act (SGMA) in 2014 marked another significant milestone in the District’s evolution. Semitropic has played a leadership role in implementing sustainable groundwater management by organizing as a Groundwater Sustainability Agency (GSA) and working with other GSAs within the Kern Subbasin to develop a Groundwater Sustainability Plan that integrates groundwater banking with long-term basin sustainability. The District’s existing conjunctive use infrastructure and decades of operational experience have provided a strong foundation for achieving SGMA’s goals while maintaining agricultural productivity and regional water reliability.
Looking Forward
Today, Semitropic Water Storage District continues to innovate through groundwater banking, local conjunctive use activities, water supply reliability projects, and sustainable groundwater management. The District remains committed to supporting California agriculture, protecting groundwater resources, and partnering with local, regional, and statewide water agencies to improve water resilience for future generations.
As climate variability increases and water supplies become more unpredictable, Semitropic’s integrated approach to groundwater banking and agricultural water management will continue to serve as a model for California’s water future.