California Department of Water Resources (DWR) | July 29th, 2016
Summary
California remains significantly dependent upon surface water. A review of the California Water Balance Summary, 2001-2010 (California Water Plan Update 2013, Volume 1, C
California remains significantly dependent upon surface water. A review of the California Water Balance Summary, 2001-2010 (California Water Plan Update 2013, Volume 1, Chapter 3, Table 3-2), indicates that in an average year like 2010, about 65 maf (million acre-feet) (more than 80 percent) of 80 maf total dedicated and developed water supply is associated with surface water. Surface storage is an essential element of managing the state’s surface water resources.
The naturally arid conditions found in much of California, coupled with seasonal variations of too much or too little water prompted water planners of the past to implement conveyance and storage projects to support land development, population, and economic growth. After construction, these dams captured seasonal runoff and stored it for beneficial uses during drier times. Today, these projects facilitate a larger set of water management objectives including reliable water supplies, water quality and ecosystem maintenance, flood management, and hydropower generation.
In many areas of the state, surface water and groundwater are used conjunctively. Coordinated surface water and groundwater management can be either formal or informal. For example, a managed groundwater recharge program where surface water is infiltrated to an aquifer for later use is formal; excess applied surface water in agricultural areas during wetter years that increases the availability of groundwater in drier years is often more informal.
Dams and surface water storage continue to be a critical tool for providing water management flexibility in California. The amount of surface water in California, as noted above, often make it a foundational integration element of more diverse local and regional water management portfolios. In addition to storing water for use by residents, businesses, and industries, these facilities provide vital supplies during warm and dry periods for growing crops and maintaining the state’s managed wildlife refuges.