Tracy Nishikawa (Former Employee)
Science and Products
Evaluation of the groundwater resources of the Petaluma Valley
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...
Determining Water Availability in the Russian River Watershed
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 Valley Surface Water/Groundwater-Flow Model
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.
Assessing the Feasibility of Artificial Recharge and Storage and the Effectiveness and Sustainability of Insitu Arsenic Removal in the Antelope Valley, California
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...
Warren Subbasin Groundwater Recharge
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).
Assessing the Feasibility of Artificial Recharge and Storage and the Effectiveness and Sustainability of Insitu Arsenic Removal in the North Buttes Area, Antelope Valley, 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.
Filter Total Items: 38
Hydrologic and geochemical characterization of the Petaluma River watershed, Sonoma County, California Hydrologic and geochemical characterization of the Petaluma River watershed, Sonoma County, California
Executive Summary The objectives of the study are to (1) develop an updated assessment of the hydrogeology and geochemistry of the Petaluma valley watershed (PVW) and (2) develop an integrated hydrologic model for the PVW. The purpose of this report is to describe the conceptual model of the hydrologic, hydrogeologic, and water-quality characteristics of the PVW and a numerical...
Authors
Jonathan A. Traum, Nicholas F. Teague, Donald S. Sweetkind, Tracy Nishikawa
Volcanic Aquifers of Hawai‘i—Construction and calibration of numerical models for assessing groundwater availability on Kaua‘i, O‘ahu, and Maui Volcanic Aquifers of Hawai‘i—Construction and calibration of numerical models for assessing groundwater availability on Kaua‘i, O‘ahu, and Maui
Steady-state numerical groundwater-flow models were constructed for the islands of Kaua‘i, O‘ahu, and Maui to enable quantification of the hydrologic consequences of withdrawals and other stresses that can place limits on groundwater availability. The volcanic aquifers of Hawai‘i supply nearly all drinking water for the islands’ residents, freshwater for diverse industries, and natural...
Authors
Scot K. Izuka, Kolja Rotzoll, Tracy Nishikawa
Santa Barbara and Foothill groundwater basins Geohydrology and optimal water resources management—Developed using density dependent solute transport and optimization models Santa Barbara and Foothill groundwater basins Geohydrology and optimal water resources management—Developed using density dependent solute transport and optimization models
Groundwater has been a part of the city of Santa Barbara’s water-supply portfolio since the 1800s; however, since the 1960s, the majority of the city’s water has come from local surface water, and the remainder has come from groundwater, State Water Project, recycled water, increased water conservation, and as needed, seawater desalination. Although groundwater from the Santa Barbara and...
Authors
Scott R. Paulinski, Tracy Nishikawa, Geoffrey Cromwell, Scott E. Boyce, Zachary P. Stanko
Evaluation of the Source and Transport of High Nitrate Concentrations in Ground Water, Warren Subbasin, California Evaluation of the Source and Transport of High Nitrate Concentrations in Ground Water, Warren Subbasin, California
Ground water historically has been the sole source of water supply for the Town of Yucca Valley in the Warren subbasin of the Morongo ground-water basin, California. An imbalance between ground-water recharge and pumpage caused ground-water levels in the subbasin to decline by as much as 300 feet from the late 1940s through 1994. In response, the local water district, Hi-Desert Water...
Authors
Tracy Nishikawa, Jill N. Densmore, Peter Martin, Jonathan C. Matti
Natural recharge estimation and uncertainty analysis of an adjudicated groundwater basin using a regional-scale flow and subsidence model (Antelope Valley, California, USA) Natural recharge estimation and uncertainty analysis of an adjudicated groundwater basin using a regional-scale flow and subsidence model (Antelope Valley, California, USA)
Groundwater has provided 50–90 % of the total water supply in Antelope Valley, California (USA). The associated groundwater-level declines have led the Los Angeles County Superior Court of California to recently rule that the Antelope Valley groundwater basin is in overdraft, i.e., annual pumpage exceeds annual recharge. Natural recharge consists primarily of mountain-front recharge and...
Authors
Adam J. Siade, Tracy Nishikawa, Peter Martin
Storage and mobilization of natural and septic nitrate in thick unsaturated zones, California Storage and mobilization of natural and septic nitrate in thick unsaturated zones, California
Mobilization of natural and septic nitrate from the unsaturated zone as a result of managed aquifer recharge has degraded water quality from public-supply wells near Yucca Valley in the western Mojave Desert, California. The effect of nitrate storage and potential for denitrification in the unsaturated zone to mitigate increasing nitrate concentrations were investigated. Storage of water
Authors
John A. Izbicki, Alan L. Flint, David R. O’Leary, Tracy Nishikawa, Peter Martin, Russell D. Johnson, Dennis A. Clark
Science and Products
Evaluation of the groundwater resources of the Petaluma Valley
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...
Determining Water Availability in the Russian River Watershed
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 Valley Surface Water/Groundwater-Flow Model
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.
Assessing the Feasibility of Artificial Recharge and Storage and the Effectiveness and Sustainability of Insitu Arsenic Removal in the Antelope Valley, California
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...
Warren Subbasin Groundwater Recharge
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).
Assessing the Feasibility of Artificial Recharge and Storage and the Effectiveness and Sustainability of Insitu Arsenic Removal in the North Buttes Area, Antelope Valley, 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.
Filter Total Items: 38
Hydrologic and geochemical characterization of the Petaluma River watershed, Sonoma County, California Hydrologic and geochemical characterization of the Petaluma River watershed, Sonoma County, California
Executive Summary The objectives of the study are to (1) develop an updated assessment of the hydrogeology and geochemistry of the Petaluma valley watershed (PVW) and (2) develop an integrated hydrologic model for the PVW. The purpose of this report is to describe the conceptual model of the hydrologic, hydrogeologic, and water-quality characteristics of the PVW and a numerical...
Authors
Jonathan A. Traum, Nicholas F. Teague, Donald S. Sweetkind, Tracy Nishikawa
Volcanic Aquifers of Hawai‘i—Construction and calibration of numerical models for assessing groundwater availability on Kaua‘i, O‘ahu, and Maui Volcanic Aquifers of Hawai‘i—Construction and calibration of numerical models for assessing groundwater availability on Kaua‘i, O‘ahu, and Maui
Steady-state numerical groundwater-flow models were constructed for the islands of Kaua‘i, O‘ahu, and Maui to enable quantification of the hydrologic consequences of withdrawals and other stresses that can place limits on groundwater availability. The volcanic aquifers of Hawai‘i supply nearly all drinking water for the islands’ residents, freshwater for diverse industries, and natural...
Authors
Scot K. Izuka, Kolja Rotzoll, Tracy Nishikawa
Santa Barbara and Foothill groundwater basins Geohydrology and optimal water resources management—Developed using density dependent solute transport and optimization models Santa Barbara and Foothill groundwater basins Geohydrology and optimal water resources management—Developed using density dependent solute transport and optimization models
Groundwater has been a part of the city of Santa Barbara’s water-supply portfolio since the 1800s; however, since the 1960s, the majority of the city’s water has come from local surface water, and the remainder has come from groundwater, State Water Project, recycled water, increased water conservation, and as needed, seawater desalination. Although groundwater from the Santa Barbara and...
Authors
Scott R. Paulinski, Tracy Nishikawa, Geoffrey Cromwell, Scott E. Boyce, Zachary P. Stanko
Evaluation of the Source and Transport of High Nitrate Concentrations in Ground Water, Warren Subbasin, California Evaluation of the Source and Transport of High Nitrate Concentrations in Ground Water, Warren Subbasin, California
Ground water historically has been the sole source of water supply for the Town of Yucca Valley in the Warren subbasin of the Morongo ground-water basin, California. An imbalance between ground-water recharge and pumpage caused ground-water levels in the subbasin to decline by as much as 300 feet from the late 1940s through 1994. In response, the local water district, Hi-Desert Water...
Authors
Tracy Nishikawa, Jill N. Densmore, Peter Martin, Jonathan C. Matti
Natural recharge estimation and uncertainty analysis of an adjudicated groundwater basin using a regional-scale flow and subsidence model (Antelope Valley, California, USA) Natural recharge estimation and uncertainty analysis of an adjudicated groundwater basin using a regional-scale flow and subsidence model (Antelope Valley, California, USA)
Groundwater has provided 50–90 % of the total water supply in Antelope Valley, California (USA). The associated groundwater-level declines have led the Los Angeles County Superior Court of California to recently rule that the Antelope Valley groundwater basin is in overdraft, i.e., annual pumpage exceeds annual recharge. Natural recharge consists primarily of mountain-front recharge and...
Authors
Adam J. Siade, Tracy Nishikawa, Peter Martin
Storage and mobilization of natural and septic nitrate in thick unsaturated zones, California Storage and mobilization of natural and septic nitrate in thick unsaturated zones, California
Mobilization of natural and septic nitrate from the unsaturated zone as a result of managed aquifer recharge has degraded water quality from public-supply wells near Yucca Valley in the western Mojave Desert, California. The effect of nitrate storage and potential for denitrification in the unsaturated zone to mitigate increasing nitrate concentrations were investigated. Storage of water
Authors
John A. Izbicki, Alan L. Flint, David R. O’Leary, Tracy Nishikawa, Peter Martin, Russell D. Johnson, Dennis A. Clark