Measuring and Monitoring

In 1998, all urban creeks in the San Francisco Bay Area were added to the Clean Water Act Section 303d list due to known or suspected diazinon impairment. Diazinon is an organophosphorus insecticide used on lawns, and fruit and vegetables. This pesticide has since been "phased out" and has not been available for purchase since late 2004. Diazinon use is declining and is being replaced by other...

The USGS has been collecting specific conductance (salinity) and water temperature data in San Francisco Bay (SF Bay) since 1990. Data are typically collected at 5-10 fixed locations throughout the bay, every fifteen minutes, every minute of the day.

This project aims to characterize spatial heterogeneity for key water quality parameters, and pilot the use of underway-flowthrough mapping of biogeochemical properties as a cost-effective approach to monitoring.

Monitoring habitat quality in the San Francisco Estuary (SFE) and Sacramento-San Joaquin Delta has been limited to mostly monthly discrete measurements of biologically relevant parameters (e.g. phytoplankton, dissolved organic matter (DOM), nutrients) that cannot fully characterize the physical and biogeochemical variability.

This study will utilize the unique analytical capabilities of the USGS Pesticide Fate Research Group (PFRG), Organic Chemistry Research Laboratory (OCRL) to assess the occurrence of a large suite of understudied, current-use pesticides and pesticide degradates in surface waters entering the Sacramento/San Joaquin Delta.

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.

Our purpose is to investigate what controls the distribution and abundance of fish prey within the Cache Slough Complex (CSC).

Our objective is to determine the relative propensity of sediment material formed under two different in situ coagulation treatments (iron sulfate, polyaluminum chloride) to release MeHg into surface waters under environmentally relevant conditions that may affect flocculant stability and MeHg production rates.

The objectives of this study are to quantify and characterize (1) phytoplankton production on Liberty Island, (2) utilization and transformation of nutrients, and (3) attenuation/loss of phytoplankton as the material is transported from Liberty Iisland into Cache Slough.

The USGS partners with local, state, and other federal agencies through cooperative agreements for a variety of reasons. The USGS and partners jointly plan the scientific work conducted under cooperative agreements resulting in science that has broad relevance to address current water issues. Partners choose to work with the USGS because of the agency's broad technical expertise, its long-standing...

The USGS has been a leader in the development of hydrologic and geochemical simulation models since the 1960's. USGS models are widely used to predict responses of hydrologic systems to changing stresses, such as increases in precipitation or ground-water pumping rates, as well as to predict the fate and movement of solutes and contaminants in water.

Land subsidence has been ongoing in the dry lake beds throughout the Mojave and Morongo groundwater basins since the 1960s. In a study conducted from 2004 - 2009, continuous GPS stations were added to interferometric synthetic aperture radar (InSAR) methods to measure changes in land surface altitude.