Growers

Recharge for Growers

The Issue 

In many parts of California, especially the San Joaquin Valley, groundwater is being pumped faster than it can be replenished. This overdraft leads to declining groundwater levels, increased pumping costs, and long-term threats to the viability of agriculture. As the Sustainable Groundwater Management Act (SGMA) is implemented, farmers are facing increasing pressure to reduce groundwater use and adopt practices that protect groundwater resources. 

Recharge as a Solution 

By participating in groundwater recharge efforts, growers can be part of the solution to sustainably manage aquifers. During wet periods, growers can spread excess surface water onto the land, facilitating percolation through the soil and replenishing aquifers. This practice helps support long-term water security. Recharge is not a one-size-fits-all solution, but for many growers, it can be an effective part of a broader groundwater management strategy. 

Recharging for Growers: Considerations 

Successfully implementing micro-basins and on-farm recharge involves a few key factors: 

Recharge Methods: There are two primary mechanisms for intentional groundwater recharge. On-farm recharge (spreading excess surface water or floodwater onto farmland) takes place on active farmland, and is often a less costly method to implement, but cannot recharge water as quickly as more direct methods. Micro-basins (dedicated basins for receiving and infiltrating water) require less land area, and are capable of recharging water faster, but they are more permanent installations and are often costlier to install. Micro-basins often pose reduced risk to groundwater quality as well. Consider what forms of recharge make sense for regional needs and constraints. 

Water Availability: Recharge typically occurs when excess surface water is available, such as during or immediately after high-flow storm events, or when reservoirs release excess water in wet years. Many irrigation districts provide access to surface water for recharge purposes when excess water is available. Growers should coordinate directly with the district to understand any benefits associated with doing recharge, such as a credit on theirsurface water bill or a credit on their groundwater pumping allocation.  

During declared flood emergencies, under Water Code 1242.1 growers may be able to divert directly from waterways but they may not have the ability to pump it out later.  

Diversions from waterways require specific water rights or temporary permits to divert. 

Surface Water Conveyance: To conduct recharge on a parcel of land, it must have access to conveyance infrastructure or natural waterways that allow for diversion of the water onto that land. Consider planning recharge projects in areas near such conveyance.  

Soil Infiltration and Topography: Soils with high infiltration rates—like sandy or loamy soils—allow more water to percolate down to aquifers. When conducting on-farm recharge, minimal slopes will also support better infiltration and reduce erosion from runoff. Sloping areas unsuitable for on-farm recharge may still be suitable for installing micro-basins and/or swales and berms. 

Crop Health: For on-farm recharge, some crops tolerate winter flooding better than others. For example, recharge on vineyards and orchards during dormancy may be feasible, and fields planted with annual crops later in the spring may support winter flooding. 

Water Quality: If conducting on-farm recharge (i.e., diverting floodwater to active farmland for recharge), the recharged water has the potential to move contaminants from the soil into the deeper aquifer, potentially harming groundwater quality. In some cases, recharge can improve groundwater quality by diluting concentrations of contaminants already in the groundwater supply. To mitigate the risk of contamination, best practices for fertilizer and pesticide applications should be established on the land. Repeated recharge on the same sites can also minimize the risk of contamination from new sites.  When planning to recharge, consult tools such as the Nitrogen Leaching Hazard Index as well as any recent applications of pesticides that are prohibited in recharge areas.   

Subsurface Conditions: The geology beneath recharge areas is important to consider, to ensure that water applied to the surface can reach the aquifer. Groundwater flow paths, depth to groundwater, and connections between the surface and the aquifer all affect recharge suitability.  

Spatial Data: GRAT Viewer (Land IQ Groundwater Recharge Suitability)