1991. The December 14, 1989, eruption of Redoubt volcano produced ash clouds that disrupted air traffic and darkened the skies intermittently for 5 months. Flooding on the Drift River caused by snow and ice melt from the volcanic activity resulted in the closing of the Drift River Oil Terminal, which is the storage and shipping center for oil wells in Cook Inlet.

In response to the Exxon Valdez oil spill in Prince William Sound, a joint Federal-State Board of Trustees, formed from land management agencies, was established under the authority of the Comprehensive Environmental Response, Compensation, and Liability Act of 1980. The Board established an Exxon Valdez Oil Spill Damage Assessment Team, which was assigned responsibility for all operations related to the disaster assessment effort. One of the first acts of the team was to establish a Geographic Information and Mapping Technical Group, comprising Federal and State land and resource management agencies as well as the USGS Alaska Field Office in Anchorage.

Initially, the group prepared a series of maps that depicted four types of information. relevant to the oil spill: (1) shoreline sensitivity information from the NOAA Environmental Sensitivity Index Map Series, (2) oil-impact data from the Alaska Department of Conservation, (3) land ownership information, and (4) coastline information derived from 1:63,360-scale USGS maps.

The USGS served as the host site for data base compilation, integration, analysis, and design and production of maps for the damage assessment team. Through the efforts of the USGS and its cooperators, a single integrated map was produced for each of the 180 1:63,360-scale quadrangles covering the 1,500 miles of shoreline affected by the oil spill. Long-term data-base management was assumed by the Alaska Department of Natural Resources. The USGS has retained the original data as backup and for use by other agencies that continue to assess and monitor cleanup activities.

During the eruption of Redoubt volcano, digital data from a NOAA weather satellite were used to monitor the distribution of ash in the atmosphere. This information was combined with coastline and elevation information to help scientists monitor the activities of the volcano (see "Redoubt Volcano, Alaska," p. 12).

Both the Exxon Valdez oil spill and the Redoubt volcano eruption underscore the value of sound earth science information and scientific cooperation in coping with natural and manmade disasters.

A Perspective for the 1990's

By David A. Rickert

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The protection and enhancement of the quality of the Nation's surface and ground water are high-priority concerns of the public and government. Since 1970, Congress has passed several acts that created regulatory programs aimed at curtailing the entry of point-source pollution into our waters. These programs have the interrelated, basic goals of maintaining or enhancing the quality of surface and ground water and protecting aquatic resources and human health.

Twenty years ago the major water-quality concerns were low dissolved oxygen content and accelerated eutrophication of specific rivers, lakes, and estuaries. Accordingly, considerable time and money were spent to reduce oxygen-demanding wastes and plant nutrients from municipal and industrial point sources. These expenditures have abated the worst of gross point-source pollution, but more subtle, complex problems have become evident. During the 1980's, the effects of acid precipitation, a nonpoint source, were observed, investigated, and politically debated.

The Nation faces a new water-quality challenge in the 1990's-how to reduce contamination from potentially toxic trace elements and manmade trace organic substances that enter surface and ground water largely from nonpoint sources, such as urban storm drainage and agricultural and forestry practices.

Water-Quality Information

The Water Quality Act of 1987 reauthorized and amended the Clean Water Act of 1977 and switched the focus of new waterquality regulations in the United States from point to nonpoint sources. The U.S. Environmental Protection Agency administers the Water Quality Act. Section 316 of the Act requires each State to develop and implement a plan to identify and limit pollution from nonpoint sources. In addition, in 1989, President Bush announced a major multiagency water-quality initiative, administered by the

The total water-quality effort of the USGS includes research, monitoring, and assessment, which together provide an understanding of water-quality problems and are the basis for evaluating resource-management decisions.

• Research. To provide an understanding of fundamental physical, chemical, and biological processes and rates.

Monitoring. To continually measure water-quality conditions over space and time by using networks that are fixed station and fixed in time.

• Assessment.-To define the status and trends of water quality and the causes of observed conditions and trends by building on research and monitoring.

Research

Water-quality research in the USGS is primarily conducted under the water resources National Research Program and the Toxic Substances Hydrology program.

National Research Program (NRP).— Improves the understanding of the nature and rates of physical, chemical, and biological processes that affect the movement of water and chemical constituents through hydrologic systems so that appropriate methods can be developed to predict the effects of natural and man-induced stresses. The NRP is functionally divided into six research disciplines: surface-water hydrology, ground-water hydrology, surface-water chemistry, groundwater chemistry, geomorphology and sediment transport, and ecology.

Toxic Substances Hydrology Program.Provides increased understanding of the occurrence, movement, and fate of hazardous substances in the Nation's surface and ground water. Program efforts consist of small-scale field studies of point-source contamination that has resulted in waste plumes in ground water and degraded stream reaches and regional-scale field studies of the occurrence and movement of toxic substances and the controlling of natural and human factors.

Monitoring

The USGS operates the only two national monitoring networks that measure surfacewater quality, the Hydrologic Benchmark Network and the National Stream Quality Accounting Network.

Hydrologic Benchmark Network (HBN).Consists of 58 sites for water quantity and quality data collection in relatively small, pristine watersheds. The HBN identifies longterm water-quality trends over time in areas unaffected by in-basin activities and provides a baseline with which to compare basins directly impacted by man. The HBN consists

of fixed stations having fixed sampling schedules, consistent methods for collecting samples, and a consistent schedule for analysis of field parameters, major ions, nutrients, trace elements, and coliform bacteria (no trace organics are measured). The HBN provides a commitment to long-term data collection, analysis, and interpretation.

National Stream Quality Accounting Network (NASQAN).-Consists of 411 active stations where outflows from most of the major rivers of the country, both to other rivers and to the oceans, are measured. NASQAN identifies long-term water-quality trends in the major rivers of the country, relates the trends to upstream land and water use, and accounts for transport (fluxes) of measured constituents off the continent and to critical estuaries and the Great Lakes.

In addition to HBN and NASQAN, the USGS coordinates and operates part of the Federal National Trends Network for acid precipitation, from which weekly samples of wet deposition are collected and analyzed from 150 network sites nationwide.

Assessment

While research and monitoring are wellestablished approaches that provide an understanding of environmental processes and conditions, these approaches do not provide the depth and breadth of information necessary to address important technical and policy questions at a national scale. Research is exhaustively detailed, usually areally limited, and open ended over time. In contrast, monitoring can provide broad areal coverage and continuing observations over time, but it does not provide insight into explanations or causes. Assessment fills the critical void between research and monitoring, building on knowledge of processes to explain observations by identifying factors and defining cause and effect.

To date, most water-quality assessment has been conducted through the USGS Federal-State Cooperative Program. This program, established in 1895, manages agreements wherein State and local agencies provide at least one-half of the funding for USGS investigations on statewide and local resource issues. As such, the program provides a commitment for funding and allows flexibility in monitoring and assessing those issues of greatest local and national concern.

In 1990, the USGS has agreements with nearly 1,000 agencies. Many of the current investigations include assessing water-quality conditions in a particular river reach or part of an aquifer. These studies include extensive data acquisition that form the core of State monitoring programs, interpretation of new

and existing data, and computer modeling of hydrologic systems to understand the probable consequences of various management actions. In many States, the cooperative program has provided extensive long-term data bases that are extremely valuable for regional and national assessments.

Water-quality assessments have been conducted by many agencies, academia, and the private sector in the United States for about 100 years. Most previous water-quality assessments, however, have addressed local problems, and all have been limited in Scope and scale. A national, perennial water-quality assessment has never been attempted and, in this absence, important national-in-scope technical and policy questions are left unanswered.

Challenges of a National
Water-Quality Assessment

Assessing the Nation's water quality is formidable. The land area to be assessed is vast, water quality varies over space and time, water-quality problems are numerous, and field work and laboratory analyses, especially those for trace organic chemicals, are expensive.

The dual challenge of managing a large area and water-quality variability can be lessened because many national issues are actually repetitive problems from different climatic or geohydrologic environments that represent specific regions of the country. For example, most questions relevant to national policy on the occurrence of pesticides can be answered by studying a few types of crops, each treated. with a typical array of applied pesticides, in a few climatic or geohydrologic regions. Those questions left unanswered by these small-scale studies can then be addressed by combining information to cross regional boundaries to the national scale.

Most field research occurs at the local (river reach or ground-water contaminant plume) scale. In contrast, most water-quality monitoring occurs at the statewide (study unit to regional) or national scales. To date, waterquality assessments generally have been conducted at the local scale. The water-quality program of the USGS is unique because it fully integrates research, monitoring, and assessment and is conducted at all scales.

Information derived from the other scales can be integrated at the national level only if certain factors are consistent within a national framework. These factors are (1) common study approaches, (2) common protocols for field and laboratory analysis, including descriptions of sampling sites, (3) consistent records of ancillary information, (4) data storage in national files, and (5) a nationally

consistent set of water-quality constituents. Certain water-quality constituents and issues are of concern only in certain areas of the country; therefore, the USGS has stipulated a national set of constituents that can be added to or reduced, as appropriate, at the other scales. At each areal scale, the NAWQA program will result in different information products: statistical descriptions, geographic descriptions, and explanations of observed conditions.

Why the USGS?

The USGS is ideally suited to conduct a national, perennial water-quality assessment because it has

• Experience in managing national waterquality networks,

• A national water-resources research program, a large portion of which is focused on the chemical, biological, and morphological fundamentals of water quality,

An existing national water-quality program that measures the quantity and flow of surface and ground water and provides the hydrologic basis needed to conduct chemical and biological studies,

A nationally distributed field staff trained to collect and interpret chemical and biological data (see map, p. 22),

In-depth experience in surface-water, ground-water, and linked surface- and ground-water studies,

Experience in water-quality assessments at the local and statewide scales,

• No regulatory jurisdiction, and

• Experience working across political boundaries on multi-State river basins and aquifers.

NAWQA Program Design

The NAWQA program will provide a nationally consistent description of current water-quality conditions for a large part of the Nation's water resources, define long-term trends (or lack of trends) in water quality, and identify, describe, and explain the major factors that affect observed water-quality conditions and trends. In some cases, the program also will enable hydrologists to define specific cause and effect relations.

NAWQA combines the surface-water and ground-water investigations of 60 areas around the country that incorporate about 60 percent of the Nation's population and water use (see map, p. 23). Study units range in size from a few thousand to several tens of thousands of square miles. By conducting the national program as an aggregation of individual studies, NAWQA results will be useful in understanding and managing important river basins and aquifers, as well as in