Publications

Biotic communities and environmental conditions can be highly variable between natural ecosystems. The variability of natural assemblages should be considered in the interpretation of any ecological study when samples are either spatially or temporally distributed. Little is known about biotic variability in the Santa Ana River Basin. In this report, the lotic community and habitat...

Stream temperature is an important component of salmonid habitat and is often above levels suitable for fish survival in the Lower Klamath River in northern California. The objective of this study was to provide boundary conditions for models that are assessing stream temperature on the main stem for the purpose of developing strategies to manage stream conditions using Total Maximum...

Concentrations of halogenated volatile organic compounds (VOCs) were determined by gas chromatography (GC) with an electron-capture detector (GC-ECD) and by gas chromatography with mass spectrometry (GC-MS) in 109 groundwater samples from five study areas in the United States. In each case, the untreated water sample was used for drinking-water purposes or was from a monitoring well in...

Throughout the world, coastal resource managers are encouraging the restoration of previously modified coastal habitats back into wetlands and managed ponds for their ecosystem value. Because many coastal wetlands are adjacent to urban centers and waters used for human recreation, it is important to understand how wildlife can affect water quality. We measured fecal indicator bacteria...

In semiarid regions, the contribution of infiltration from intermittent streamflow to ground water recharge may be quantified by comparing simulations of fluid and heat transport beneath stream channels to observed ground temperatures. In addition to quantifying natural recharge, streamflow infiltration estimates provide a means to characterize the physical properties of stream channel...

The surface renewal method was used to estimate evapotranspiration (ET) for a restored marsh on Twitchell Island in the Sacramento–San Joaquin Delta, California, USA. ET estimates for the marsh, together with reference ET measurements from a nearby climate station, were used to determine crop coefficients over a 3‐year period during the growing season. The mean ET rate for the study...

Despite their trophic importance and potential importance as bioindicators of stream condition, benthic algae have not been well studied in California. In particular there are few studies from small streams in the Sierra Nevada. The objective of this study was to determine the standing crop of chlorophyll-a and benthic algal species assemblages present in the small 1st- and 2nd-order...

Historically, California’s Central Valley has been one of the most productive agricultural regions in the world. The Central Valley also is rapidly becoming an important area for California’s expanding urban population. During 1980–2007, the population nearly doubled in the Central Valley, increasing the competition for water. Because of the importance of ground water in the Central...

Rainfall samples were collected during the 2003 and 2004 growing seasons at four agricultural locales across the USA in Maryland, Indiana, Nebraska, and California. The samples were analyzed for 21 insecticides, 18 herbicides, three fungicides, and 40 pesticide degradates. Data from all sites combined show that 7 of the 10 most frequently detected pesticides were herbicides, with...

Seasonal fluctuations of plant biomass and photosynthesis are key features of the Earth system because they drive variability of atmospheric CO2, water and nutrient cycling, and food supply to consumers. There is no inventory of phytoplankton seasonal cycles in nearshore coastal ecosystems where forcings from ocean, land and atmosphere intersect. We compiled time series of phytoplankton...

Occurrence and fate of 45 pesticides and 40 pesticide degradates were investigated in four contrasting agricultural settings—in Maryland, Nebraska, California, and Washington. Primary crops included corn at all sites, soybeans in Maryland, orchards in California and Washington, and vineyards in Washington. Pesticides and pesticide degradates detected in water samples from all four areas...

Debris flows generated during rain storms on recently burned areas have destroyed lives and property throughout the Western U.S. Field evidence indicate that unlike landslide-triggered debris flows, these events have no identifiable initiation source and can occur with little or no antecedent moisture. Using rain gage and response data from five fires in Colorado and southern California...