Upper workings of the Pennsylvania Mine in the headwaters of Peru Creek, Colorado. USGS scientists have developed an improved approach for identifying the major sources of contaminants to streams in watersheds, such as this one, impacted by acid mine drainage. Photograph by Robert L. Runkel, USGS.
A former uranium mill tailings site near Rifle, Colorado, is next to the Colorado River. A team of scientists has documented multiple chemical reactions that transform hexavalent uranium to more insoluble forms of tetravalent uranium in the subsurface at the site. Photo credit: John Bargar, SLAC National Accelerator Laboratory.
A USGS scientist collects a water sample for analysis of mineral particles know as colloids. Toxic metals (such as copper in excess) bind to the particles, which are then ingested by aquatic animals. Photo credit: Daniel Cain, USGS.
Diffusive Gradients in Thin Films (DGT) samplers deployed in High Ore Creek, Montana, accumulated dissolved metals during deployment, enabling scientists to do a time-integrated evaluation of varying concentrations of metals in the stream. Photo credit: Laurie Balistrieri, USGS.
The influx of metal-rich groundwater from natural springs (foreground) to Cement Creek, Colorado (background) can complicate the selection of best management practices. USGS scientists have developed methods for evaluating strategies to reduce acid mine drainage in streams. Photo credit: Briant Kimball, USGS.
Big Hole River in southwestern Montana. USGS scientists and their university colleagues have shown that photosynthesis by aquatic plants causes large diel (daily) cycles in pH, dissolved oxygen concentrations, and the isotopes of oxygen and carbon. In addition, the aquatic plants are thought to cause large changes in streamflow as oxygen production during photosynthesis stiffens the plants and thereby retards downstream flow during the day.
Deposit of iron-cemented stream gravel (ferricrete) with embedded wood fragments that can be age dated using radiocarbon to determine the age of the ferricrete deposit. Knowing the age of the ferricretes helps scientists determine if the associated enrichment of metals in streams occurred before or after mining in the watershed started.
The Silver Ledge Mine in the area of upper Mineral Creek, near Silverton, Colorado, is one of many abandoned mine sites in the watershed. USGS scientists have developed methods for identifying the largest sources of acid mine drainage amongst many in a watershed. Photo credit: Philip Verplanck, USGS.
Mineral Creek watershed in southwestern Colorado has natural and mining-related sources of contamination. In the background of this photo is a large naturally occurring seep that discharges acidic, metal-rich water to a tributary of Mineral Creek. Natural sources of contamination like this one make it difficult to determine appropriate water-quality standards for cleanup actions.
Field experiment designed to compare survival of trout fry (newly hatched fish) exposed to constant versus varying metal concentrations, High Ore Creek, Montana Water stored in the streamside tanks was used to refresh plastic containers in the stream. Water in the tanks had high, medium, or low metal concentrations. The fourth tank contained metal-free water used as an experimental control.
Scientists checking fish held in plastic containers that were exposed to a constant metal concentration as part of a field experiment to compare survival of trout fry (newly hatched fish) exposed to constant versus varying metal concentrations, High Ore Creek, Montana.
Fish held in flow-through containers are exposed to metal concentrations with daily high and low cycles (diel cycles). Scientists conducted a field experiment to compare survival of newly hatched trout (fry) exposed to constant versus varying metal concentrations, High Ore Creek, Montana The experiment will help scientists understand the effect of diel variations in the concentration of metals on fish in mining affected areas.
A field experiment in Mineral Creek, Colorado, used 18 drive point wells along a 33-meter study reach to sample for groundwater inflow to the stream of metal-rich water (copper, zinc, and other metals) from abandoned mine sites. Identification of such inflows, when no surface manifestation occurs, is one of the applications of stream-tracer injections.
USGS scientists display some of their precautions used to prepare a sodium hydroxide solution. The solution was used for a pH modification experiment in Mineral Creek, Colorado. The pH modification experiment was designed to study the changes in geochemical conditions that affect the transport of metals in streams during remediation of acidic mine drainage.
Solutions of lithium bromide (right tank) and sodium hydroxide (left tank) used for of a pH-modification experiment in Mineral Creek, Colorado. The experiment was designed to simulate remediation of acid mine drainage systems that artificially raise the pH of streams.
Green ferrous iron hydroxide precipitate forming downstream from the injection of sodium hydroxide base (white tubing in stream) into metal-rich, acidic Mineral Creek, Colorado. The injection of the base solution is an analog for mine drainage cleanup programs that use limestone and other materials to raise the pH of streams to conditions that support fish habitat.
A field experiment in August 2005 tested the injection of sodium hydroxide base into the metal-rich, acidic (low pH) Mineral Creek, Colorado. Green ferrous iron hydroxide precipitate formed downstream from the injection point (white tubing in stream). A reactive solute-transport model, OTEQ, was used to predict the changes that occurred in the acidic stream when the pH is raised by the injection of the high pH solution (basic solution).
Before a pH modification experiment conducted in Mineral Creek, Colorado, the pH of the stream was about 3.0, and the streambed was heavily coated with aluminum and iron precipitates. Mineral Creek receives acid mine drainage from abandoned mine lands and is one of the streams that USGS scientists are studying to understand the factors that influence the transport of metals in acidic streams.
During a pH modification experiment conducted in Mineral Creek, Colorado, the pH of the stream changed from about 3.0 to about 8.0 (acidic to mildly basic). The change in pH caused the older precipitates in the stream to be covered by a new precipitate (ferrous iron hydroxide). A solution of a base (sodium hydroxide) was injected into the stream to change the pH.
USGS scientists collecting water-quality samples from drive point wells along a 30-meter reach of Mineral Creek, Colorado. The wells were located near pits along the streambed to characterize the quality of groundwater entering the stream.
Graph of the increasing number of papers in hydrology journals that reference work by the USGS on the hyporheic zone, transient storage, and/or the solute transport modeling code OTIS.
Conceptual diagram of biological processes from sources to receptors in the catchment, stream system. Metal sources from the watershed are transported to the aquatic ecosystem in water and sediments. Within the aquatic ecosystem, these metals then affect organisms within the food web.
One of the basic questions for understanding contamination from hardrock mining relates to mined versus unmined sources of metals. This view of Red Mountain No. 3, near Silverton, Colorado, shows the complex nature of the problem. Extensive alteration of bedrock can produce acid rock drainage, while mines, like the Yankee Girl mine shown here (lower half of photo), dot the terrain producing acid mine drainage.
An important part of quantifying the loading of metals to streams is to identify and characterize inflows along the stream. Inflows can range from dispersed seeps, to subsurface inflow from groundwater discharging into the stream, to large seeps from iron bogs such as the one shown in this view along Red Mountain Creek, near Silverton, Colorado.
A USGS scientist and a volunteer sample metal-rich water from a seep draining a pile of mine tailings along Silver Creek, near Park City, Utah. Seeps such as this one can come from tailings piles that are remnants of past mining activities. Contaminants from hardrock mining can come from adits, waste rock piles, and from tailings that were stored along streams.
Cement Creek, Colorado, is a site of USGS investigations of the fate of acid mine drainage. USGS scientists are developing methods to characterize contaminated streams that can be used by water-resource managers to make better cleanup decisions.
Acid mine drainage from Cement Creek (upper left) mixes with the waters of the Animas River, Colorado (right) in 1997. Chemical reactions creating the yellow and orange colloids in this mixing zone affect the transport of contaminants down the Animas River.
Detailed vertical sampling across a mixing zone as acid, metal-rich water from Cement Creek (left) joins near-neutral water of the Upper Animas River (right), near Silverton, Colorado. Reactions in mixing zones affect the transport of metals for hundreds of kilometers downstream.
Scenic view of the Upper Animas River watershed, Silverton, Colorado -- one of the watersheds in the USGS Abandoned Mine Lands Initiative.
A small mountain stream impacted by acid mine drainage, Prospect Gulch, Upper Animas River watershed, Colorado.
USGS scientists processing water samples during a stream tracer test on California Gulch, Upper Animas River watershed, Colorado.
Collecting fish samples for toxicity testing with an electrofishing unit in the Upper Animas River, Colorado.
Locating inflows and springs discharging into Mineral Creek, Colorado, prior to conducting a tracer test. Tracer tests are used to assess the relative magnitude of metal loading from inflows along a stream reach.
An abandoned structure and waste-rock pile from the Silverledge Mine adjacent to Mineral Creek, Colorado.
A site of continuous water-quality sampling during a tracer test conducted on the North Fork of the Animas River, Colorado.
View of a data logger used to control a pump that injects a tracer solution into a stream during a stream tracer test.
Collecting invertebrate samples to assess the community composition of a mining-impacted stream, Upper Animas River watershed, Colorado.
USGS equipment trailer -- bringing tracer tests to Rocky Mountain streams.
One of the "obstacles" facing USGS scientists studying the impact of abandoned mine sites on Rocky Mountain watersheds, Mineral Creek, Colorado.
Spacing sampling points along a stream prior to a tracer test on Mineral Creek, Colorado.
Filling a holding tank with a tracer solution prior to the start of a stream tracer study, Upper Animas River watershed, Colorado.
Abandoned mine site in the Boulder River watershed, Montana -- one of the watersheds in the USGS Abandoned Mine Lands Initiative.
Crystal Mine at Uncle Sam Gulch, Boulder River watershed, Montana.
Comet Mine Mill, Montana, with glory hole where valley-fill tailings were placed.
Mill tailings deposited on the flood plain of Basin Creek in the Boulder River watershed, Montana, 1998. USGS geologist and U.S. Forest Service engineer are discussing scientific findings of the USGS Abandoned Mine Lands Initiative and implications for remediation being planned by the U.S. Forest Service for the Buckeye mine and mill tailings.
Reclaimed flood plain and stream channel at former site of the Buckeye mill tailings, 2002. Cleanup efforts conducted in 2000-01 by the USDA Forest Service dramatically reduced erosion of metal-rich tailings into Basin Creek, Montana.
A view of Pinal Creek Valley, Arizona, (circa 1990s) showing mine workings, large waste pile, and encroaching development of Globe, Arizona.
A view of Pinal Creek Valley, Arizona, (circa 1900) showing mine workings and valley floor.
Measuring the water chemistry of Pinal Creek, Arizona, the site of an investigation of the discharge of an acidic groundwater plume to the creek.
Perennial reach of Pinal Creek, Arizona, where water from an acidic plume of groundwater is discharged.
Propane injection test used to quantitatively measure the degassing of dissolved gases from Pinal Creek, Arizona.
View of the setup of a NaCl tracer test that was designed to determine natural attenuation of metals in Pinal Creek, Arizona.
Downstream view of Pinal Creek, Arizona, where a tracer solution was injected into the stream during a tracer test. Water-quality sampling crews can be seen in the distance.
MINIPOINT groundwater sampler used to measure metals attenuation in shallow streambed sediments.
Discharge of treated water from a remediation system designed to treat a plume of acidic groundwater, Pinal Creek, Arizona.
A view of the Arkansas River, Colorado, in which the water chemistry and sediments have been affected by drainage from abandoned mine lands.
Mine dump at St. Kevin Gulch, Colorado, (Upper Arkansas River watershed) the location of USGS research on the transport of metals in streams impacted by acid mine drainage.