Hydrologic Modeling

Project Update - 8/2/2011: Water having an arsenic concentration of 30 micrograms per liter was infiltrated from a test pond beginning in December, 2010. After water moved downward through the unsaturated zone, arsenic concentrations in Lysimeters as deep as 110 ft beneath the pond were about 2 micrograms per liter. Laboratory column experiments show similar changes in arsenic concentrations in...

Biofuels, including ethanol, are expected to provide a greater contribution to the fuel supply in the United States. Research in the past decade has shown that ethanol in gasoline can cause plumes of benzene in groundwater to be larger than they would otherwise be.

The U.S. Army at Fort Irwin National Training Center (NTC) obtains all of its potable water supply from Irwin, Langford, and Bicycle Basins within the base boundaries. Groundwater pumping, since as early as 1941, has resulted in water-level declines in all of these basins and the disposal of treated wastewater in the Irwin Basin has resulted in elevated nitrate concentrations in some wells in...

The U.S. Fish & Wildlife Service's (USFWS) San Francisco Bay National Wildlife Refuge manages wildlife at a number of salt ponds that the Cargill Corporation currently operates for salt production. A number of these ponds probably will be purchased by the USFWS. With acquisition, the USFWS will be responsible for maintenance or restoration of thousands of hectares of wetlands, an extremely complex...

The endeavor to ensure a viable population of the threatened wolverine to the mountains of California requires the characterization of suitable habitat.

The Santa Ana River in Southern California is the primary water supply for approximately 2 million people. The main constituent of regulatory concern is pathogens that have impaired the use of waters for the beneficial uses of warm freshwater habitat and noncontact water recreation. Pathogen loadings from the tributary watershed flows into lakes and streams leading into the Santa Ana River...

The Sonoma County Water Agency (SCWA) and the San Francisco District office of the U.S. Army Corps of Engineers (CORPS) have identified issues associated with sedimentation in the lower Laguna de Santa Rosa and Mark West Creek in Sonoma County. Human activities in the watershed over the last 200 years have accelerated erosion and sediment delivery to the Laguna reducing the water storage capacity...

San Gorgonio Pass Water Agency (SGPWA) covers an area of 220 square miles in the mountain pass between the Upper Santa Ana River Basin to the west and the Coachella Valley to the east. Since 1961, when the SGPWA was formed, demand for ground water has increased with the increase in population within the agency boundaries. To prepare for future demands for water, the SGPWA has proposed to...

Using the new information, along with the recently acquired seismic reflection data, USGS scientists and co-workers have been able to develop a much more detailed understanding of the stratigraphy and structure of the Central and West Coast Basins.

The Mountains Recreation and Conservation Authority (MRCA) is considering plans for developing a new park at the confluence of the Los Angeles River and the Arroyo Seco. These plans include removing channel lining and creating a temporary lake using an inflatable rubber dam. Before implementing the plan, a wide array of scientific and engineering issues must be addressed. The U.S. Geological...

The Hi Desert Water District (HDWD) provides water service to about 10,000 customers in the areas of Yucca Valley, Yucca Mesa, and some unincorporated areas of San Bernardino County. The study area is the 19 square mile Warren subbasin of the Morongo groundwater basin (approximately 100 miles east of Los Angeles, California).

The USGS works in cooperation with local, State, and Federal agencies to compile and disseminate data on the Nation's water use. The annual water-use estimates are reported at the county, State, and national levels and provide fundamental input to regional hydrologic models. These estimates commonly represent the largest stresses in most aquifers and are needed by local managers to steward the...