Steve Ackley (Former Employee)

Groundwater has been the primary source of domestic, agricultural, and municipal water supplies in the southwestern Mojave Desert, California, since the early 1900s. The population of the Mojave River and Morongo groundwater basins has grown rapidly during the last several decades, increasing from an estimated population of almost 273,000 in 1990 (Mojave Water Agency, 2004) to more than 453,000 in...

The purpose of the proposed work is to collect data that will support the development, calibration, and validation of numerical models of sediment transport and turbidity in the Sacramento-San Joaquin Delta.

The National Park Service (NPS) and USGS jointly will investigate impacts to the Merced River due to infrastructure and historic channel widening in east Yosemite Valley with a goal of constructing river management alternatives. Past management actions, such as gravel mining, channel riprap, and the construction of bridges that do not accommodate flood flows, have had long-lasting impacts to the...

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 U.S. Fish & Wildlife Service's (USFWS) San Francisco Bay National Wildlife Refuge manages wildlife at a number of salt ponds that the Cargill Corporation currently operates for salt production. A number of these ponds probably will be purchased by the USFWS. With acquisition, the USFWS will be responsible for maintenance or restoration of thousands of hectares of wetlands, an extremely complex...

The endeavor to ensure a viable population of the threatened wolverine to the mountains of California requires the characterization of suitable habitat.

Malibu Lagoon and near-shore ocean water in Malibu, Calif. have concentrations of fecal indicator bacteria (FIB) that occasionally exceed public health standards for recreational water.

Traditional methods for measuring coarse bedload sediment transport by discrete physical sampling tend to be labor intensive and expensive (Gray and others, 2010). As such, bedload samples often are collected too infrequently to capture the temporal variability inherent in transport rates, which can vary significantly, sometimes by a factor of ten or more, over time periods of several minutes to...

Water from the Sacramento-San Joaquin Delta contains high concentrations of disinfection byproduct-forming (DBP-forming) materials when treated for potable use. DBPs form when dissolved organic compounds (DOC) in water react with disinfectants such as chlorine and ozone during the water treatment process. The amount of DBPs that form is a function of both the amount and source of the DOC, both of...

The Santa Ana River in Southern California is the primary water supply for approximately 2 million people. The main constituent of regulatory concern is pathogens that have impaired the use of waters for the beneficial uses of warm freshwater habitat and noncontact water recreation. Pathogen loadings from the tributary watershed flows into lakes and streams leading into the Santa Ana River...

Pyrethroid insecticide use in California has been increasing in recent years. Pyrethroids are used in both agricultural and urban areas. They are of environmental concern because of their high toxicity to fish and invertebrates.

The Sonoma County Water Agency (SCWA) and the San Francisco District office of the U.S. Army Corps of Engineers (CORPS) have identified issues associated with sedimentation in the lower Laguna de Santa Rosa and Mark West Creek in Sonoma County. Human activities in the watershed over the last 200 years have accelerated erosion and sediment delivery to the Laguna reducing the water storage capacity...