Tracy Nishikawa

The city of Petaluma, located in the Petaluma Valley and home to about 12 percent of the population of Sonoma County, faces growth in population and demand for water. Water supply is provided primarily by water delivered via aqueduct from the Russian River; however, groundwater is a vital supplemental source of water for the city of Petaluma and is the primary source of supply for domestic and...

The Russian River Watershed covers 1,500 square miles of urban, agricultural and forested lands in northern Sonoma County and southern Mendocino County, California. Communities in the Russian River Watershed (RRW) depend on a combination of Russian River water and groundwater to meet their water-supply demands. Water is used primarily for agricultural irrigation, municipal and private wells supply...

Sonoma County faces potential changes in surface-water availability, including potential impacts on water quality in response to changing land use, increasing population, and climate change.

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...

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).

Groundwater pumpage for agricultural and municipal supply has resulted in water-level declines of more than 200 ft in some parts of the Antelope Valley groundwater basin and land subsidence of more than 6 ft in some areas. Future urban growth, increased agricultural demand, and limits on the supply of imported water will continue to increase the demand for groundwater.

Prior to 1997, local surface water and groundwater supplied all of the water supply for the city of Santa Barbara (about 120 miles northwest of Los Angeles). Excess pumping of groundwater during times of drought resulted in saltwater intrusion in Storage Unit I of the Santa Barbara groundwater basin.