Surface Water

The U.S. Geological Survey Toxic Substances Hydrology Program has conducted periodic reconnaissance studies of streams in 10 midwestern states to determine the geographic and seasonal distribution of herbicide compounds.

Small fractions, estimated at <1 to 2% of the pesticides applied to Midwestern cropland are lost from fields and enter nearby streams during rainfall events. In many cases aquatic organisms are exposed to mixtures of chemicals, which may lead to greater non-target risk than that predicted based on traditional risk assessments for single chemicals. Relatively little research has been directed at...

The Blue River drains approximately 680 square miles west of the Continental Divide in central Colorado before flowing northward into the Colorado River near Kremmling, Colorado. The Blue River watershed (BRW) is almost entirely located in Summit County and includes the towns of Breckenridge, Dillon, Frisco, Montezuma, and Silverthorne. Dillon Reservoir and Green Mountain Reservoir are major water...

Elevated loads of salt and selenium can impair the quality of water for both anthropogenic and natural uses. Understanding the environmental processes controlling how salt and selenium are introduced to streams is critical to managing and mitigating the effects of elevated loads. Dominant relations between salt and selenium loads and environmental characteristics can be established by using...

The Hydrologic Benchmark Network (HBN) was established in 1963 to provide long-term measurements of streamflow and water quality in areas of the United States that are minimally affected by human activities.

The South Platte River Basin study, conducted as part of the U.S. Geological Survey's National Water-Quality Assessment Program, combines information on water chemistry, physical characteristics, stream habitat, and aquatic life to provide science-based insights for current and emerging water issues in surface waters (streams, rivers, reservoirs) and groundwaters of the South Platte River Basin...

The water quality of the Vallecito Reservoir watershed in southwestern Colorado was initially studied by the U.S. Geological Survey (USGS) during July 1996 to July 1997, in cooperation with the Pine River Irrigation District, to assess the suitability of the reservoir as a potential source of drinking water (Ranalli and Evans, 1999). As a result of this study, in December 1997 a group of residents...

OTIS is a mathematical simulation model used to characterize the fate and transport of water-borne solutes in streams and rivers. The governing equation underlying the model is the advection-dispersion equation with additional terms to account for transient storage, lateral inflow, first-order decay, and sorption. This equation and the associated equations describing transient storage and sorption...

Fluvial tailings deposits stored in the floodplain of the upper Arkansas River represent a potential nonpoint source of contamination to surface and ground waters. The U.S. Geological Survey has been cooperating with the U.S. Environmental Protection Agency to monitor a lowcost, insitu remediation technique for the deposits.

The USGS Abandoned Mine Lands Initiative (AMLI) is developing and demonstrating scientific knowledge and technologies that will help Federal land management agencies clean up contamination in areas near abandoned hardrock mines across the Nation. The Initiative is being conducted in two pilot watersheds, the Upper Animas River Basin in Colorado and the Boulder River watershed in Montana, where the...