Publications

This report presents Phase 2 of the review and development of the mass balance water-quality model, originally developed in 2001, that guided establishment of the phosphorus (P) total maximum daily load (TMDL) for Upper Klamath and Agency Lakes, Oregon. The purpose of Phase 2 was to incorporate a longer (19-year) set of external phosphorus loading data into the lake TMDL model than had...

The U.S. Geological Survey, in cooperation with the Colorado Water Conservation Board, evaluated the predictive uncertainty of mean-monthly streamflow-regression equations representative of natural streamflow conditions in Colorado. This study evaluates the predictive uncertainty of mean-monthly streamflow-regression equations developed in a 2009 U.S. Geological Survey study using...

In 2011, the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, collected samples for 12 new argon-argon radiometric ages from eastern Snake River Plain olivine tholeiite basalt flows in the subsurface at the Idaho National Laboratory. The core samples were collected from flows that had previously published paleomagnetic data. Samples were sent to Rutgers...

Digital surfaces and thicknesses of selected hydrogeologic units of the Floridan aquifer system were developed to define an updated hydrogeologic framework as part of the U.S. Geological Survey Groundwater Resources Program. The dataset contains structural surfaces depicting the top and base of the aquifer system, its major and minor hydrogeologic units and zones, geophysical marker...

The hydrogeologic framework for the Floridan aquifer system has been revised throughout its extent in Florida and parts of Georgia, Alabama, and South Carolina. The updated framework generally conforms to the original framework established by the U.S. Geological Survey in the 1980s, except for adjustments made to the internal boundaries of the Upper and Lower Floridan aquifers and the...

Juvenile Chinook Salmon Oncorhynchus tshawytscha emigrating from natal tributaries of the Sacramento River, California, must negotiate the Sacramento-San Joaquin River Delta (hereafter, the Delta), a complex network of natural and man-made channels linking the Sacramento River with San Francisco Bay. Fish that enter the interior and southern Delta—the region to the south of the...

From 1966 to 2002, activities at the Standard Chlorine of Delaware chemical facility in New Castle County, Delaware resulted in the contamination of groundwater, soils, and wetland sediment. In 2005, the U.S. Geological Survey (USGS), in partnership with the U.S. Environmental Protection Agency, Region 3, and the Delaware Department of Natural Resources and Environmental Control began a...

This report presents the results of a study to provide information on the hydrologic effects of potential 21st-century changes in climate, water use, and land cover in the Upper Scioto River Basin, Ohio (from Circleville, Ohio, to the headwaters). A precipitation-runoff model, calibrated on the basis of historical climate and streamflow data, was used to simulate the effects of climate...

During 2005-8, the U.S. Geological Survey, in cooperation with the Cambridge, Massachusetts, Water Department, measured concentrations of sodium and chloride, plant nutrients, commonly used pesticides, and caffeine in base-flow and stormwater samples collected from 11 tributaries in the Cambridge drinking-water source area. These data were used to characterize current water-quality...

The Rainfall-Response Aquifer and Watershed Flow Model (RRAWFLOW) is a lumped-parameter model that simulates streamflow, spring flow, groundwater level, or solute transport for a measurement point in response to a system input of precipitation, recharge, or solute injection. I introduce the first version of RRAWFLOW available for download and public use and describe additional options...

The U.S. Geological Survey, in cooperation with the Alabama Department of Agriculture and Industries, sampled a network of 15 wells for up to 167 pesticides and pesticide degradates from 2009 through 2013 in three areas of high-density row-crop agriculture in Alabama. Eighteen herbicides, 2 fungicides, and 9 degradates were detected in water from the sampled wells. The highest...

Groundwater recharge is one of the most difficult components of a water budget to ascertain, yet is an important boundary condition necessary for the quantification of water resources. In Minnesota, improved estimates of recharge are necessary because approximately 75 percent of drinking water and 90 percent of agricultural irrigation water in Minnesota are supplied from groundwater. The...