Measuring and Monitoring

The USGS has a long history of collecting water-level data in the Antelope Valley groundwater basin. Previous water-level contour maps for Antelope Valley were published by the USGS in cooperation with the Antelope Valley – East Kern Water Agency as Open-File Reports 80-1222, 86-498 and 98-4022 using water-level data collected in 1979, 1984 and 1996, respectively. An updated water-level contour...

The Bureau of Land Management (BLM) manages the Dos Palmas Oasis complex on the northeastern side of the Salton Sea for the maintainence of threatened and endangered species. This Oasis complex represents a rare area of riparian/wetland habitat in the midst of an extremely arid desert region. Anthropogenic development of water resources during the 1900s depleted natural groundwater supplies...

The Rim Fire has burned over 400 square miles of the Tuolumne River and Merced River watersheds in central California and is now the 3rd largest wildfire in state history. The burn area is largely on the Tuolumne between Hetch Hetchy Reservoir and Don Pedro Reservoir, both of which serve as critical sources of drinking water and irrigation water to San Francisco Bay area and Central Valley...

The Tulare Lake basin in the southern Central Valley of California is heavily dependent upon groundwater for drinking water supply but groundwater in this basin is threatened by a wide array of issues. Groundwater aquifers in the alluvial fan sediments derived from the Sierra Nevada on the eastern side of the Tulare Lake basin are highly productive aquifers that are vulnerable to contamination...

Pesticides are used throughout the State of California in both urban and agricultural settings and are routinely detected in surface water. Each year, new pesticides are introduced to the market and often become detected in surface water. It can take several years or more for routine monitoring programs to acquire the capability to detect new and understudied pesticides of concern because...

Runoff from snowmelt and rainfall in the Tuolumne River basin plays a significant role in irrigation and domestic water supply for Turlock and Modesto Irrigation Districts, City of Modesto and the San Francisco Bay Area. This area experiences very different seasonal and decadal climate events which are known to affect the timing and volumes of runoff. Land-cover change alone, such as the Rim Fire...

The atmosphere plays an important role in the delivery to and cycling of mercury (Hg) in the environment and it can be a major source of Hg contamination to surface waters. Globally, atmospheric deposition of Hg is the primary source of Hg related concerns for human and ecosystem health (Fitzgerald and others, 1998). In California and other areas in the United States, Hg use in gold and silver...

Dredging to maintain water storage capacity by the Nevada Irrigation District (NID) occurred at Lake Combie reservoir, one of several reservoirs along the Bear River, California over the past 40 years on an as-needed basis to maintain water storage capacity. Maintenance dredging operations were halted by the Central Valley Regional Water Quality Control Board (CVRWQCB) in 2002 because of elevated...

Suspended-sediment measurements are essential for coastal planning, resource management, and for assessing the sustainability of salt marshes in relation to expected sea-level rise. Suspended sediment can have positive or negative effects, depending on its characteristics and amount, and on the location and ecosystem services of interest. Sediment deposition in salt marshes helps sustain marsh...

The East Bay Municipal Utility District (EBMUD) has proposed to store and recover as much as 10 million gallons of water per day (MGD) at an aquifer storage and recovery (ASR) site, the Bayside Groundwater Project. Water will be stored in a 100-ft sequence of coarse-grained sediment (the "Deep Aquifer") underlying the East Bay Plain and the adjacent Niles Cone ground-water basin.

Previous studies have detected current-use pesticides and DDT metabolites in water and suspended sediments from the Alamo and New Rivers. Additional studies have found water samples from both rivers to be toxic to aquatic organisms in laboratory bioassays, and implicated certain current-use pesticides as the source of this toxicity. Recent requirements under the Clean Water Act for the Regional...

Measurements of elevations, aquifer-system compaction, and water levels are used to improve our understanding of the processes responsible for land-surface elevation changes. Elevation or elevation-change measurements are fundamental to monitoring land subsidence.