USGS Monthly Groundwater News and Highlights: August 1, 2015

Featured Product: USGS California Drought Web Site

If you've been following the news lately, you've probably heard that California is in the midst of one of the worst droughts in the state's recorded history. (A drought is a period of drier-than-normal conditions that results in water-related problems.) The ongoing drought is affecting water supplies and ecosystems around the state. Declining groundwater levels have resulted in land subsidence (see photos below), and some wells in the Central Valley -- a key agricultural region -- have gone dry. The Governor declared a drought State of Emergency last year, and mandatory water-use restrictions are in place around the state.

Scientists from the USGS California Water Science Center are closely monitoring the effects of the California drought through data collection and research around the state. Our hydrologists use the data and information they collect now, combined with historical data and scientific tools such as groundwater models, to improve our understanding of the current drought in the context of long-term hydrologic, climatic, environmental changes, and to forecast future conditions. USGS science is being used by California water managers and policy makers to support successful planning and science-based decision-making to respond to the drought and plan for the future.

For the latest USGS science on this important topic, visit the USGS California Water Science Center's drought web site.

USGS Groundwater-Related Press Releases

New Groundwater Model Provides Better Understanding of Edwards Aquifer

Drainage of Prairie Pothole Wetlands Can Increase Flooding and Degrade Ecosystems

Congressional Hearings, Briefings, and Statements

July 31, 2015: Using Every Drop of Information: the Open Water Data Initiative

USGS Groundwater-Related Publications

Hydrogeology of the Susquehanna River valley-fill aquifer system in the Endicott-Vestal area of southwestern Broome County, New York

Groundwater levels, trends, and relations to pumping in the Bureau of Reclamation Klamath Project, Oregon and California

Effects of groundwater pumping on agricultural drains in the Tule Lake subbasin, Oregon and California

Lithostratigraphic, borehole-geophysical, hydrogeologic, and hydrochemical data from the East Bay Plain, Alameda County, California

Updated numerical model with uncertainty assessment of 1950-56 drought conditions on brackish-water movement within the Edwards aquifer, San Antonio, Texas

Water-level altitudes 2015 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2014 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

Water resources during drought conditions and postfire water quality in the upper Rio Hondo Basin, Lincoln County, New Mexico, 2010-13

Simulation of groundwater flow and chloride transport in the "1,200-foot" sand with scenarios to mitigate saltwater migration in the "2,000-foot" sand in the Baton Rouge area, Louisiana

Delineation of areas having elevated electrical conductivity, orientation and characterization of bedrock fractures, and occurrence of groundwater discharge to surface water at the U.S. Environmental Protection Agency Barite Hill/Nevada Goldfields Superfund site near McCormick, South Carolina

Hydrologic conditions in Rhode Island during water year 2014

Annual and average estimates of water-budget components based on hydrograph separation and PRISM precipitation for gaged basins in the Appalachian Plateaus Region, 1900-2011

Hydrogeology, groundwater levels, and generalized potentiometric-surface map of the Green River Basin lower Tertiary aquifer system, 2010-14, in the northern Green River structural basin

Water levels of the Ozark aquifer in northern Arkansas, 2013

Installation of a groundwater monitoring-well network on the east side of the Uncompahgre River in the Lower Gunnison River Basin, Colorado, 2012

Metamodels to bridge the gap between modeling and decision support

Groundwater quality in Geauga County, Ohio: status, including detection frequency of methane in water wells, 2009, and changes during 1978-2009

Geostatistical borehole image-based mapping of karst-carbonate aquifer pores

The Effect of modeled recharge distribution on simulated groundwater availability and capture

Chloride concentrations, loads, and yields in four watersheds along Interstate 95, southeastern Connecticut, 2008-11: factors that affect peak chloride concentrations during winter storms

Field Photos:

Land subsidence is a gradual settling or sudden sinking of the Earth's surface owing to subsurface movement of earth materials. These photos were taken at two of five benchmark locations used to help measure the largest recent land subsidence in the San Joaquin Valley, California, using repeat surveys. Hydrologist Michelle Sneed is holding signs that indicate how far the ground has settled over the years indicated; the signs also show how the rate of land subsidence at these locations increased in recent years. The exact maximum subsidence location in the region is unknown; however, the 5 benchmark sites have the largest magnitude measured in the last 5 years.

The USGS used satellite-based interferometric synthetic aperture radar (InSAR) images to further characterize this large subsidence bowl first seen by California Department of Water Resources surveys northeast of the Delta-Mendota Canal. The InSAR images processed by USGS indicate that this bowl is much larger than originally believed, encompassing roughly 1,200 square miles and includes part of the canal. Centered near the town of El Nido, California, it is bounded roughly by the towns of Merced on the north, Mendota on the south, Los Banos on the west and Madera on the east. It also includes part of the San Joaquin River, most of the Eastside bypass — the primary flood control channel east of the river — and other water conveyance structures. At the center of the subsidence bowl near El Nido (pictured), the rate of subsidence in this area — nearly 1 foot a year — is among the highest ever measured in the San Joaquin Valley. Continued subsidence could cause infrastructure damage in local communities as well as adversely affect the already subsided canal area. (For the detailed study, refer to Sneed and others, 2013)

Learn more:

USGS California Land Subsidence Monitoring Network

Delta-Mendota Canal: Evaluation of Groundwater Conditions & Land Subsidence

Overview of land subsidence - USGS national fact sheets and related reports