Minerals-Related Contamination

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ater of the Alamosa River, which runs through the San Luis Valley

in southwestern Colorado, is used extensively for irrigation, domestic purposes, and water supply to the Alamosa National Wildlife Refuge and nearby wetlands. Increasing concentrations of heavy metals and acid in the river water, attributed to recent mining at Summitville, Colo., have drawn national attention. These environmental problems are compounded by the erosion of natural sources of highly mineralized rocks in the San Juan Mountains and by contamination from historical mining. To address these problems, the USGS has begun site-specific studies at the now-abandoned Summitville mine and detailed geologic and geophysical work in the San Luis Valley.

At Summitville, USGS scientists are evaluating the contamination problems at and downstream from the mine. Geologists and geophysicists are working on a detailed map of the fracture systems and chemically toxic zones at the mine site to establish the hydrologic paths of contaminated water. These studies will provide information for onsite remediation by the Environmental Protection Agency (EPA). The USGS also is providing information to the EPA on the concentrations of chemical elements that have not been monitored previously in the Summitville drainages, on the geologic and geochemical processes that control the drainage chemistries, and on baseline geochemical conditions now present on the site before any reclamation or remediation.

The San Luis Valley downstream from the Summitville mine is being examined to determine the extent and effects of metal contamination in wetlands of the Alamosa National Wildlife Refuge and adjacent farms and forests. The studies are providing information on the changes in soil geochemistry that have resulted from the recent mining. Scientists are analyzing the metal content of tree rings from nearby forests to evaluate changes that have occurred through time. Other studies include monitoring the concentration and mobility of metals in irrigationditch sediments and ponds and comparing the metal concentrations in crops irrigated by Alamosa River water with those of crops irrigated by other sources.

SGS geologists organized and taught an environmental geochemistry course in late April 1993 to more than 100 geologists, environmental consultants, regulators, and governmental officials concerned about minimizing the environmental impacts of mineral development. The course focused on the geochemical and biogeochemical processes that control how mineral deposits and mining byproducts interact with the environment. This course was one of several held in conjunction with the Society of Economic Geologists international meeting “Integrated Methods in Exploration and Discovery" in Denver, Colo.

The USGS continues to increase the effectiveness and accessibility of its nonfuel mineral-resource information. In FY 1993, the Minerals Information Offices (see p. 107 for locations) completed minerals-related research for 3,398 clients affiliated with industry and other business interests, government agencies, academia, trade associations, and the general public. Custom searches of the Mineral

The Summitville mine and its downstream environmental effects in the San Luis Valley, Colo.

determinations of magnetic declination (the difference between true north and magnetic north) are required for all maps and charts. Numerous Federal agencies require detailed geomagnetic data for statutory missions, including the operation of satellites.

The USGS operates 11 magnetic observatories, conducts magnetic field surveys to determine rates of changes in the magnetic field components, and works with other Federal agencies to obtain satellite data as part of a worldwide data collection effort. The USGS National Geomagnetic Information Center, located in Denver, Colo., collaborates with 30 international observatories to collect and exchange satellite data and makes these international data readily available to users in the United States.

In addition to the data collection projects, the USGS Magnetic Field Monitoring and Charting program funds research on a wide variety of topics. Variations in the geomagnetic field enable scientists to study many types of geologic processes, whose time spans range from mere seconds to millions of years, from deep within the Earth's core to the far reaches of space. Such studies include research on electromagnetic dynamo models of the Earth's molten core in an attempt to explain the origin of planetary magnetic fields; field polarity reversals, which are vitally important to paleomagnetic, archeomagnetic, and paleoclimatic research; conductivity of the Earth's crust and mantle; mathematical modeling to predict changes in the field; development of magnetic monitoring and measuring equipment, including data acquisition systems and methods; and relationships between solar-induced geomagnetic disturbances and long-term global weather patterns.

The program provides advice and information to people in other governmental agencies, the academic community, and the private sector. Services provided include the calibration of magnetic instruments, recommendations on the installation and operation of magnetic equipment and data acquisition systems, and advice on methods for identifying and eliminating magnetic influences on satellite spacecraft.

World Magnetic Charts Available

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series of world magnetic charts published in 1993 shows the magnetic declination, horizontal and vertical intensities, inclination, and total field intensity components of the Earth's magnetic field. These charts display contours of the absolute values of each component for the current magnetic epoch. Additionally, each chart displays contours of the average rate of change in that component, so that a user can compute a localized field value for a short period of years before and after the epoch date of the chart.

To improve the data available to its users, the National Geomagnetic Information Center, with the support and cooperation of other agencies, established new magnetic observatories in Hungary, Brazil, and India to fill large gaps in global data availability. These observatories are owned and operated by the countries in which they are located. The data are available in near real time for use by USGS researchers and other users in the United States.

and measure ice cores, and it preserves these ice samples in a long-term repository for present and future investigations. The cores are stored in a continuously monitored cold room at a controlled temperature of -31 °F. In an adjacent laboratory kept at a more temperate climate. of -10 °F, scientists can examine the 1-meter lengths of cores in "relative comfort." The laboratory's data base can be accessed remotely by telephone, so that researchers throughout the world can review repository holdings.

The laboratory, housed at the USGS Denver facility, curently holds more than 10,000 meters of ice cores from the polar caps of Antarctica and Greenland, including the world's deepest ice core, the GISP2, from central Greenland. Climate records now being reconstructed from the GISP2 core have fundamentally changed the way scientists view climate change and indicate that major shifts in temperature and precipitation can occur in as few as 5 years rather than centuries, as previously thought. These ice cores also provide the only known direct record of atmospheric changes over the last 250,000 years.

To access the base computer models developed in publishing these magnetic charts, call 1 (800) 358-2663.

For more information on monitoring and charting the Earth's magnetic field, contact Donald Herzog at:

Telephone (303) 273-8487
Internet herzog@gldfs.cr.usgs.gov

For more information on the ice-core laboratory, contact:

Telephone (303) 236-5562
Internet jfitz@bpgsvr.cr.usgs.gov

John Wood

coordinates the USGS Magnetic Field Monitoring and Charting program and has written extensively on the Earth's magnetic properties

Ice-Core Laboratory Dedication

limate changes can result from both

human actions (emissions of carbon dioxide, methane, and other greenhouse gases) and natural events (volcanic eruptions or meteorite impacts). By studying the record of climate changes preserved in ice, scientists may be able to evaluate current changes in the atmosphere and predict future changes. To that end, the most advanced ice-core laboratory in the world was dedicated in Denver, Colo., in August 1993. A joint effort of the

National Science Foundation, the University of Colorado, and the USGS, the laboratory is the only storage and curatorial facility for ice cores in North America. The lab allows scientists to examine

Of Floods and Forecasts: Critical Water Information for the Nation

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Water-data stations at selected locations throughout the Nation are used by the USGS Hydrologic Data Collection program to obtain records on stream discharge (flow) and stage (height), including floodflow monitoring; reservoir and lake stage and storage; well and spring discharge and ground-water levels; and the quality of surface and ground water. These data provide a continuing record of the quantity and quality of the Nation's surface- and ground-water resources and thus provide the hydrologic information needed by Federal, State, and local agencies and the private sector for the development and management of land and water resources.

In cooperation with State and local agencies, the USGS collects, stores, analyzes, and disseminates data on water use for the Nation. Every 5 years since 1950, the National Water-Use Information program has prepared estimates of (1) water withdrawn from surface- and groundwater sources, (2) consumptive use, and (3) instream use and wastewater releases. These reports, the latest of which was published in 1990, are used to develop and evaluate trends in water use and to plan for more effective uses of the Nation's water resources in the future.

that will help planners and managers in the affected States recover from this year's natural disaster and plan appropriately for future floods. During the floods, the USGS furnished continuous information on streamflow and other related topics to the National Weather Service (NWS), the U.S. Army Corps of Engineers, the Federal Emergency Management Agency (FEMA), and many State and local agencies as part of its mission to provide basic data on the Nation's surface- and ground-water resources at more than 50,000 sites across the United States. The NWS uses the data in forecasting floods and issuing flood warnings. The Corps uses the data to manage water projects, such as diversions, dams, locks, and levees. FEMA and many State and local emergency management agencies use USGS hydrologic data and NWS forecasts as part of the basis of their local flood-response plans.

The flood of 1993 was the result of a series of unusual climatic factors. A wet spring followed by record-breaking rains in June and July produced more than a year's worth of precipitation in 7 months, which in turn produced the recordbreaking floods on the Mississippi River. Precipitation was as much as 200 percent of normal for the 6 months preceding the June and July storms. As a result, streamflows were also well above normal, reservoirs were filled to the point where little reserve storage capacity remained, and wet soil conditions were conducive to runoff of most of the later rainfall.

The Flood of 1993

The

he months of June to August 1993 will long be remembered by the peo

ple of the Midwest as the "Summer of the Flood." The floods, which were the result of a succession of severe storms in the upper Mississippi River Basin, were the most severe, in terms of damage, in the history of the United States. Unofficial estimates of damage to property and agricultural losses have been as high as $10 billion, and many tens of thousands of people were forced from their homes.

The flooding presented the USGS with the scientific challenge of monitoring floodwaters in extremely hazardous conditions and conducting followup studies

Extreme streamflowsones that exceeded the 100-year recurrence interval-were recorded at 45 stream-gaging stations in 9 States.

In June and July, the jet stream consistently dipped abnormally south over the Plains area east of the Rocky Mountains. That stalled weather system, coupled with a high-pressure zone in the

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