The preservation of Northern California’s groundwater resources is critical to the economic, social and environmental fabric of the region. Sacramento Valley water resources managers have conjunctively managed surface and groundwater for many years to provide groundwater sustainability and assure reliable and affordable water supplies within the region. As pressures on Sacramento Valley water supplies increase, water resources managers will more actively manage the groundwater resources in conjunction with surface supplies to assure regional sustainability and self-sufficiency.

To better understand and manage groundwater resources for local uses in the Sacramento Valley, local public agencies have adopted groundwater management plans under the AB 3030 process (Water Code §10750 et seq.) and other specific authorities.

Groundwater monitoring is an integral part of this management for the region to ensure the proper management and protection of the resource. Groundwater management is also an element of integrated regional water management programs in the Sacramento Valley. Additionally, the Legislature in 1984 adopted Water Code §1220 and counties across the region have adopted groundwater ordinances designed to protect groundwater and the health and welfare of the citizens of these areas.

In the Sacramento Valley, groundwater resources are actively managed for the safe-yield of the aquifer systems.

Groundwater Levels

In nearly all parts of the Sacramento Valley, reliable surface water supplies are the key to healthy groundwater aquifers. The ability for water resources managers to conjunctively manage surface and groundwater resources has led to stable groundwater aquifers that are operated within their safe-yield. Without these surface water supplies, many areas would be either over-drafted or trending towards overdraft conditions. In fact, the localized areas in the Sacramento Valley that have seen groundwater elevation declines are areas that do not utilize surface water.

“Historically, groundwater levels associated with the Sacramento Valley have remained steady, declining moderately during extended droughts and generally recovering to their pre-drought levels during subsequent wetter periods.” (DWR Bulletin 160-2009, SR-12.)

The California Department of Water Resources prepares and periodically updates the inventory of groundwater basins in its Bulletin 118 series—California’s Groundwater. The Sacramento Hydrologic Region is described on page 155 of California’s Groundwater, Bulletin 118 – Update 2003. Bulletin 118 Starting in 2012 groundwater level information is presented to the Department of Water Resources as part of the California Statewide Groundwater Elevation Monitoring Program (CASGEM).

Groundwater Quality

Groundwater supply is sustainable in the region. Water resources managers are incorporating water quality improvement strategies into their local and regional plans as groundwater quality is better understood.

“Groundwater quality in the Sacramento River Hydrologic Region is generally excellent. However, there are areas with local groundwater problems. Natural water quality impairments occur at the north end of the Sacramento Valley in the Redding subbasin, and along the margins of the valley and around the Sutter Buttes, where Cretaceous age marine sedimentary rocks containing brackish to saline water are near the surface. Water from the older underlying sediments mixes with the fresh water in the younger alluvial aquifer and degrades the quality. Wells constructed in these areas typically have high TDS. Other local natural impairments are moderate levels of hydrogen sulfide in groundwater in the volcanic and geothermal areas in the western portion of the region. In the Sierra foothills, there is potential for encountering uranium and radon-bearing rock or sulfide mineral deposits containing heavy metals. Human-induced impairments are generally associated with individual septic system development in shallow unconfined portions of aquifers or in fractured hard rock areas where insufficient soil depths are available to properly leach effluent before it reaches the local groundwater supply. (DWR Bulletin 118-2003.)

Resources

DWR Bulletin 118

UC Cooperative Extension Series on Groundwater

United States Geological Survey, Sustainability of Groundwater Resources, Circular 1186 (1999)

United States Geological Survey, Status of Groundwater Quality in the Southern, Middle, and Northern Sacramento Valley Study Units, 2005–08: California GAMA Priority Basin Project, by George L. Bennett, V, Miranda S. Fram, and Kenneth Belitz

Abstract: http://pubs.usgs.gov/sir/2011/5002/
Report: http://pubs.usgs.gov/sir/2011/5002/pdf/sir20115002.pdf

Groundwater Ambient Monitoring and Assessment (GAMA) / Geotracker

Map of GAMA Priority Basins

El Dorado Domestic Well Study (2003-2004)

Draft Tehama Domestic Well Study (2005)

Yuba County Domestic Well Study (2002)

NCWA Testimony to the Legislature (February 2011)

Association of California Water Agencies, Sustainability from the Ground Up: Groundwater Management in California (2011)