Decades of Data Support Westlands Groundwater Sustainability Success Jun 23, 2020 The nation’s largest agricultural water district has over half a century of data sets on groundwater conditions, which supported the development of its first groundwater sustainability plan (GSP) under the Sustainable Groundwater Management Act (SGMA). In addition to the abundance of groundwater data, Westlands Water District also has a wealth of experience in groundwater management, having proactively developed its first groundwater management plan in the 1990s and requiring meters in the early 2000s. These factors, as well as an involved public, have helped lead to the success of the Westlands Water District Groundwater Sustainability Agency (GSA). “I’m really fortunate to work for a Board that has been very proactive in groundwater management,” said Katarina Campbell, Westlands’ Supervisor of Resources, who manages the Westside Subbasin GSP. “The abundance of historical data has enabled the District to develop a robust groundwater model that has been instrumental in developing our GSP.” The GSA is still working through several critical issues as SGMA implementation moves forward, namely land subsidence and lowering groundwater levels. Before the Central Valley Project (CVP) was built in 1960s and 1970s, Westlands relied primarily on groundwater, pumping as much as 900,000 acre-feet of water per year. The CVP was developed to reduce reliance on groundwater while delivering higher-quality water to the region to support its significant agricultural production. However, decades later, as a result of regulations controlling CVP operations and drought conditions resulting in reliance on groundwater, subsidence remains a key undesirable result in the Subbasin. As the focus shifts from the development of the GSP to its implementation, the GSA will rely on a multifaceted approach in addressing key groundwater challenges. For instance, groundwater recharge will be one of the GSA’s primary focus moving forward, with three new groundwater recharge basins planned as well as other opportunities such as on-farm recharge. The Westside Subbasin GSP estimates as much as 200,000 acre-feet of water could be available to replenish the basin through the existing Aquifer Storage and Recovery Program. To reach its sustainable yield, the GSA is developing an accounting system for the Subbasin, where agricultural water customers can pump a certain amount per year based on the gross acres in the Subbasin. The system allows credits to be stored in high surface water years, when less water is pumped from the basin. Collaboration with the public and Fresno County has been, and continues to be, a key factor supporting the GSP’s success thus far. The GSA hosted more than 60 outreach events while developing the plan. Outreach and engagement will continue to be important to the work of the GSA as it moves forward with implementation in coordination with neighboring subbasins.