Images

The Central Valley Hydrologic Model (CVHM) is built on knowledge from USGS and other Federal, State, and local studies. The CVHM was constrained by comparing simulated and historically observed groundwater levels, streamflows, and subsidence.

A USGS Hydrologist re-develops a monitoring well to ensure a good hydraulic connection is present between the perforations in the well and surrounding aquifer.  This work was being done as part of a groundwater system characterization and groundwater quality study being conducted along the All-American Canal that runs through the area.

A scientist from the USGS California Water Science Center taking well water sample in California.

A USGS Hydrologist collects water-quality samples as part of a wellbore characterization test at site LCWSP2 of the Forecasting Total Dissolved Solids Concentrations of Groundwater from the Lower Colorado Water Supply Project study.

The All-American Canal in Imperial County, California near the border of Arizona and Mexico. Water discharging from well LCWSP2 can be seen on the far side of the canal.

Aerial view of the Iron Gate Dam and Hatchery along the Klamath River near Hornbrook, California.  A series of hydroelectric facilities (JC Boyle, Copco No. 1, Copco No. 2, and Iron Gate) separate the Klamath River into upper and lower basins.

Recording location and water-level data at a groundwater monitoring site in the Imperial Sand Dunes Recreation area, Imperial County, California. The work is being done as part of a water quality and groundwater system characterization study along the All-American Canal that runs through the area.

USGS scientist collecting water samples from an amphibian monitoring site in Livermore, California.

Stream gage #10254005 located near Westmorland, CA, on the eastern shore of the Salton Sea, now sits out of the water as the Salton Sea continues to evaporate and the shoreline retreats.

Schematic showing conceptual model of net infiltration illustrating the layered root-zone waterbalance model for the San Gorgonio Pass area, Riverside County California.  The INFILv3 model uses a daily water-balance model of the root zone to estimate the spatial and temporal distribution of natural groundwater recharge in a study area.

Looking east towards USGS Site ID: 340541117074401-6, Site Name: 001S002W07Q001S-6S, Local name: SBCC 1-6 in San Bernardino County, California.

Fissure near Lucerne Lake along State Route 247 (visible in background), Mojave Desert, California. The localized subsidence in five areas near dry lake beds was caused by declining water levels in fine-grained (clay and silt) sediments. In the Mojave River and Morongo Groundwater Basins (fig.

A map of subsidence in the Delta based on the leveling and observations of transmission-line foundations, circa 1930s-1990s. The subsidence increases stresses on the levee system, and failure of levees would cause salt water to move further up the Delta system by disrupting favorable gradients.

Picture of the Salinas River taken by webcam. USGS 11152500 SALINAS R NR SPRECKELS CA. Picture of the Salinas River taken by webcam. USGS 11152500 SALINAS R NR SPRECKELS CA.

The GAMA program is a comprehensive assessment of statewide groundwater quality. The program is designed to help better understand and identify risks to groundwater resources. Groundwater is sampled at many locations across California in order to characterize its constituents and identify trends in groundwater quality.

Debris Flow in Cable Canyon following the 2003 Old Fire in the San Bernardino Mountains, California.

Map of study areas and key geographic features in Sonoma and Mendocino Counties.

Groundwater is the sole source for water use to the rural community and two Native American tribes in the Cahuilla Valley and Terwilliger Valley groundwater basins, which are located approximately 35 miles southwest of Palm Springs, California.

Fine-grained sediments (clays and silts) within an aquifer system are the main culprits in land subsidence due to groundwater pumping. Fine-grained sediments are special because they are composed of platy grains. When fine-grained sediments are originally deposited, they tend to be deposited in random orientations.

Map of study area, Yucca Valley, California.

Approximate point of maximum subsidence in the San Joaquin Valley, California. Land surface subsided ~9 m from 1925 to 1977 due to aquifer-system compaction. Signs on the telephone pole indicate the former elevations of the land surface in 1925 and 1955.

Photograph by Richard Ireland, U.S. Geological Survey