Aquifer Storage and Recovery in a Balanced Water Supply Portfolio for Woodland and Davis in California's Central Valley

The communities of Woodland and Davis, California, currently utilize groundwater from the Yolo Basin as their sole water supply.  The Woodland Davis Clean Water Agency (Agency) is a joint powers authority, including the Cities of Davis and Woodland (Cities) and the University of California at Davis, formed to divert, treat and convey Sacramento River water to the Cities’ respective service areas. This project will allow the project partners to reduce their groundwater pumping rates, a shift that will facilitate compliance with existing and anticipated wastewater discharge requirements and ensure compliance with existing and anticipated drinking water standards. 

Aquifer Storage and Recovery (ASR) will improve the Agency’s operational flexibility and reliability in meeting demands during normal, dry and critical years, without placing any substantial additional demands on the overall surface water and groundwater supply of the region. Also, ASR can be used to meet peak demands that might otherwise be met with groundwater or above ground storage. If ASR is used for this latter purpose, water quality under these peak demand conditions will be better than if native groundwater had been used. ASR will also have long-term water quality benefits because, over time, injected water would replace native groundwater impaired by nitrate and naturally-occurring metallic species, including arsenic, hexavalent chromium, manganese, and selenium, with better-quality water. This is expected to result in water quality improvements in municipal wells in the vicinity of the ASR wells.

Current Agency efforts to evaluate the technical feasibility of ASR include aquifer testing (both pumping and injection testing), groundwater modeling, and geochemical evaluations.  The Agency is also coordinating with the Central Valley Regional Water Quality Control Board to design a regulatory framework that provides operational flexibility while protecting and even improving groundwater quality.