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Gregory Mendez

Gregory Mendez - California Water Science Center

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a photo of two milky-colored desert pupfish against a dark background

Investigation of Groundwater and Surface Water Interactions in Support of Ecosystem Management at San Sebastian Marsh, California

To help the U.S. Bureau of Land Management determine the long-term sustainability of the San Sebastian Marsh, and its critical role for the survival of the endangered desert pupfish (Cyprinodon macularius), the USGS is evaluating the potential interactions and relation between groundwater and surface water at the San Sebastian Marsh.
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California Water Science Center
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Investigation of Groundwater and Surface Water Interactions in Support of Ecosystem Management at San Sebastian Marsh, California

To help the U.S. Bureau of Land Management determine the long-term sustainability of the San Sebastian Marsh, and its critical role for the survival of the endangered desert pupfish (Cyprinodon macularius), the USGS is evaluating the potential interactions and relation between groundwater and surface water at the San Sebastian Marsh.
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concrete-lined river running through an industrial area

Continuous, Real-Time Water-Quality Monitoring of the Los Angeles River

As part of the Urban Waters Federal Partnership (UWFP) program, this project will bring enhanced water-quality monitoring to a stretch of the Los Angeles River slated for revitalization. The UWFP reconnects urban communities—particularly those that are overburdened or economically distressed—with their waterways by improving coordination among federal agencies.
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California Water Science Center
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Continuous, Real-Time Water-Quality Monitoring of the Los Angeles River

As part of the Urban Waters Federal Partnership (UWFP) program, this project will bring enhanced water-quality monitoring to a stretch of the Los Angeles River slated for revitalization. The UWFP reconnects urban communities—particularly those that are overburdened or economically distressed—with their waterways by improving coordination among federal agencies.
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Map of study area, Yucca Valley, California.

Determining the fate and transport of septic-tank effluent in the southern area of Warren subbasin, California

Residents and businesses in Yucca Valley, CA rely currently on septic tanks to treat their wastewater. The local water district, Hi-Desert Water District (HDWD), is planning to construct a sewer system and wastewater treatment plant, initially serving the West, Midwest, Mideast, Northeast, and East hydrogeologic units of the Warren subbasin.
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California Water Science Center
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Determining the fate and transport of septic-tank effluent in the southern area of Warren subbasin, California

Residents and businesses in Yucca Valley, CA rely currently on septic tanks to treat their wastewater. The local water district, Hi-Desert Water District (HDWD), is planning to construct a sewer system and wastewater treatment plant, initially serving the West, Midwest, Mideast, Northeast, and East hydrogeologic units of the Warren subbasin.
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Water being released into a recharge pond, Yucca Valley, California

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).
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California Water Science Center
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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).
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Photo #9 of well site YVDA being drilled

Yucaipa Valley Hydrogeology

This study assesses the quality of water in the Yucaipa area, primarily in the Yucaipa plain. This hydrogeology study will aid local water purveyors in understanding and evaluating local resources and using those resources effectively in combination with water imported from northern California and from the adjacent San Bernardino area.
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California Water Science Center
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Yucaipa Valley Hydrogeology

This study assesses the quality of water in the Yucaipa area, primarily in the Yucaipa plain. This hydrogeology study will aid local water purveyors in understanding and evaluating local resources and using those resources effectively in combination with water imported from northern California and from the adjacent San Bernardino area.
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Hydrogeologic characterization of the Yucaipa groundwater subbasin

IntroductionWater management in the Santa Ana River watershed in San Bernardino and Riverside Counties in southern California (fig. A1) is complex with various water purveyors navigating geographic, geologic, hydrologic, and political challenges to provide a reliable water supply to stakeholders. As the population has increased throughout southern California, so has the demand for water. The Yucai
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Water Resources, California Water Science Center

Geologic, hydrologic, and water-quality data from multiple-well monitoring sites in the Bunker Hill and Yucaipa Groundwater Subbasins, San Bernardino County, California, 1974–2016

In 1974, the U.S. Geological Survey (USGS), in cooperation with the San Bernardino Valley Municipal Water District, initiated a study to assess the regional groundwater resources in the Bunker Hill Subbasin of the Upper Santa Ana Valley Groundwater Basin in San Bernardino County, California. The study area expanded east into the Yucaipa Subbasin in 1996. This report compiles the geologic (borehole
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Water Resources, California Water Science Center

Geologic structure of the Yucaipa area inferred from gravity data, San Bernardino and Riverside Counties, California

In the spring of 2009, the U.S. Geological Survey, in cooperation with the San Bernardino Valley Municipal Water District, began working on a gravity survey in the Yucaipa area to explore the three-dimensional shape of the sedimentary fill (alluvial deposits) and the surface of the underlying crystalline basement rocks. As water use has increased in pace with rapid urbanization, water managers hav
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Water Resources, California Water Science Center

Water- and air-quality and surficial bed-sediment monitoring of the Sweetwater Reservoir watershed, San Diego County, California, 2003-09

In 1998, the U.S. Geological Survey, in cooperation with the Sweetwater Authority, began a study to assess the overall health of the Sweetwater watershed in San Diego County, California. This study was designed to provide a data set that could be used to evaluate potential effects from the construction and operation of State Route 125 within the broader context of the water quality and air quality
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Water Resources, California Water Science Center

A geochemical approach to determine sources and movement of saline groundwater in a coastal aquifer

Geochemical evaluation of the sources and movement of saline groundwater in coastal aquifers can aid in the initial mapping of the subsurface when geological information is unavailable. Chloride concentrations of groundwater in a coastal aquifer near San Diego, California, range from about 57 to 39,400 mg/L. On the basis of relative proportions of major-ions, the chemical composition is classified
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Water Resources, California Water Science Center

Application of a watershed model (HSPF) for evaluating sources and transport of pathogen indicators in the Chino Basin drainage area, San Bernardino County, California

A watershed model using Hydrologic Simulation Program-FORTRAN (HSPF) was developed for the urbanized Chino Basin in southern California to simulate the transport of pathogen indicator bacteria, evaluate the flow-component and land-use contributions to bacteria contamination and water-quality degradation throughout the basin, and develop a better understanding of the potential effects of climate an
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Water Resources, California Water Science Center

Water-quality data from storm runoff after the 2007 fires, San Diego County, California

The U.S. Geological Survey collected water-quality samples during the first two storms after the Witch and Harris Fires (October 2007) in southern California. The sampling locations represent an urban area (two residential sites in Rancho Bernardo that were affected by the Witch Fire; a drainage ditch and a storm drain) and a rural area (Cotton-wood Creek, which was downstream of a mobile home par
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Water Resources, California Water Science Center

Sample collection of ash and burned soils from the October 2007 southern California Wildfires

Between November 2 through 9, 2007 scientists from the U.S. Geological Survey (USGS) collected samples of ash and burned soils from 28 sites in six areas burned as a result of the Southern California wildfires of October 2007, including the Harris, Witch, Santiago, Ammo, Canyon, and Grass Valley Fires. The primary goal of this sampling and analysis effort was to understand how differences in ash a
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Spectroscopy Lab

Water- and air-quality monitoring of Sweetwater Reservoir watershed, San Diego County, California — Phase one results continued, 2001-2003

In 1998, the U.S. Geological Survey, in cooperation with the Sweetwater Authority, began a study to monitor water, air, and sediment at the Sweetwater and Loveland Reservoirs in San Diego County, California. The study includes regular sampling of water and air at Sweetwater Reservoir for chemical constituents, including volatile organic compounds (VOC), polynuclear aromatic hydrocarbons (PAH), pes
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Water Resources, California Water Science Center

Water- and air-quality monitoring of the Sweetwater Reservoir Watershed, San Diego County, California-Phase One results, continued, 1999-2001

In 1998, the U.S. Geological Survey, in cooperation with the Sweetwater Authority, began a study to assess the overall health of the Sweetwater watershed with respect to chemical contamination. The study included regular sampling of air and water at Sweetwater Reservoir for chemical contaminants, including volatile organic compounds, polycyclic aromatic hydrocarbons, pesticides, and major and trac
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Water Resources, California Water Science Center

Occurrence and distribution of pesticide compounds in surface water of the Santa Ana basin, California, 1998-2001

A study of the occurrence and distribution of pesticide compounds in surface water of the highly urbanized Santa Ana Basin, California, was done as part of the U.S. Geological Survey's National Water-Quality Assessment Program (NAWQA). One-hundred and forty-eight samples were collected from 23 sites, and analyzed for pesticide compounds during the study period from November 1998 to September 2001

An assessment of optical properties of dissolved organic material as quantitative source indicators in the Santa Ana River basin, Southern California

The ability to rapidly, reliably, and inexpensively characterize sources of dissolved organic material (DOM) in watersheds would allow water management agencies to more quickly identify problems in water sources, and to more efficiently allocate water resources by, for example, permitting real-time identification of high-quality water suitable for ground-water recharge, or poor-quality water in ne
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Organic Matter Research Laboratory
view looking down the length of a concrete-lined Los Angeles River
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