ROBERT M. HIRSCH
ASSOCIATE DIRECTOR FOR WATER
U.S. GEOLOGICAL SURVEY
DEPARTMENT OF THE INTERIOR
SUBCOMMITTEE ON FISHERIES, WILDLIFE, AND WATER
SENATE COMMITTEE ON ENVIRONMENT AND PUBLIC WORKS
UNITED STATES SENATE
November 14, 2001
Mr. Chairman and Members of the Subcommittee, thank you for the opportunity to report on the status of water conditions in the United States as monitored by the U.S. Geological Survey (USGS).
The USGS is a science agency within the Department of the Interior with a history of 122 years of providing scientific information needed for the wise management of our Nation's natural resources. The study of water goes back to our very early years and the work of our second Director, John Wesley Powell, who focused much attention on the availability of water resources for the economic development of the West. The USGS of today consists of four major program areas: Geology, Geography, Biology, and Water. The USGS strives to combine these four disciplinary areas to provide more complete information and analysis regarding the resource and environmental issues facing our Nation.
Hydrologically, conditions across the country are quite varied at the present time. The West is a mixture of above‑normal flows in southern and coastal California, normal flows in Washington State, and below‑normal flows in the northern and central Rockies, northern California and Oregon. Although the interagency U.S. Drought Monitor, which incorporates USGS streamflow information, continues to depict much of the Northwest as being in moderate to extreme drought, streamflows have moderated in some areas (such as Washington State) during the past four to six weeks. In the central third of the Nation, rivers and streams are generally flowing in the normal range, with above normal flows throughout Indiana, southern Michigan, and eastern North Dakota. Indeed, intense and persistent rains in October brought very high flows and flooding to much of the southern Great Lakes and northern Ohio Valley from the middle of October to early November The East, however, is a different story. Streams in the coastal states from Maine to Florida are reporting very low flows for this time of year, with many setting new daily and weekly records.
The USGS water resources program provides reliable, impartial, timely information that is needed to understand the Nation's water resources.
We operate about 7000 streamgages, which monitor the flow of water in our Nation's rivers and streams, and we freely provide the current and historical data to a wide range of' users. This information is used for purposes that include: water supply planning, flood risk assessment, water quality management (including calculation of Total Maximum Daily Loads under the Environmental Protection Agency's Clean Water Act Program), water supply operations, streamflow forecasting (done primarily by the National Weather Service, the Army Corps of Engineers, and the Natural Resources Conservation Set‑vice), habitat assessments, and personal planning of river‑based recreational activities. Currently, we are in a process of modernizing the streamgage network. At the present time, about 5000 of these stations have satellite telemetry that enables us to provide near‑real‑time data to all users via the Internet.
Using these data, and information from other agencies, I will describe the current surface-water situation across the Nation, as well as variations and changes that have occurred in recent weeks. To (to this I will rely on an illustration that we create daily and place on the USGS website. It is based on conditions for the preceding week at all USGS streamgaging stations that have 30 or more years of record and have telemetry systems. Each dot on the map represents an individual gage. They are color coded with red indicating that flows for the week were the lowest ever recorded for that time of year, brown indicating that flow was below the 10th percentile, orange was between the 10th and 25th percentile, green indicates "normal" (25th to 75th percentile), light blue is 75th to 90th percentile, dark blue is above the 90th percentile, and black represents record high flows for this time of year.
Figure 1. AVERAGE STREAMFLOW FOR THE WEEK ENDING NOVEMBER 12.
Average Weekly Streamflow for the
Week Ending Monday, November 12, 2001
The lowest flows currently are occurring in southern Virginia and western North Carolina. During the past several weeks, more than three‑dozen streamgages have reported new record daily and weekly low‑flows in this area. This pattern is also reflected in groundwater declines as monitored at a few USGS wells that report in realtime in this region. Other areas experiencing record low flows for this time of year include South Carolina, the Delaware River basin, and parts of New England.
What's interesting about the pattern of dryness in the East is that, although it seems to have just recently appeared, it has actually been lurking around since early summer. Along the entire Eastern Seaboard, except for South Florida, flows have been varying between normal and below normal since July. There were no persistent rainy periods, particularly those associated with tropical storm systems, to produce and maintain elevated flows and, when below‑normal to much below‑normal precipitation occurred throughout the coastal States during October, the region was poised to experience fairly rapid streamflow declines. Although the reservoirs serving some metropolitan areas are at normal to above‑normal levels for this time of year, such as those feeding the Potomac River upstream of Washington, D.C., other systems are already showing signs of stress. Just last week, for example, storage in the Upper Delaware River Basin reservoirs declined to drought warning levels, triggering reductions in Delaware River flow targets and water diversions to New York City and New Jersey.
I would like to focus for a moment on the Delaware River Basin, which encompasses more than 13,000 square miles in Delaware, New Jersey, New York, and Pennsylvania. As major river systems go, the Delaware River Basin is a small watershed ‑ covering only about 0.4 percent of the U.S. land area. Despite its small size, the Basin provides water to about 20 million people, about 7 percent of the U.S. population. Although not physically in the basin, New York City obtains about one‑half its water supply from three reservoirs in the Upper Delaware Basin. As I mentioned previously, water supplies in the Delaware River Basin are showing signs of stress. On November 1, 2001, combined storage in the Upper Delaware Basin reservoirs was 98 billion gallons, or 36 percent of capacity, and continues to decline. This is 57 percent lower than the level of storage that existed a year ago. As a result of these abnormally dry conditions, New Jersey, New York, and Pennsylvania have recently declared some level of drought alert for counties in the basin. Voluntary conservation measures are being requested in these areas. If storage continues to decline at the present rate, the Delaware River Basin could be in a drought emergency condition by early December, resulting in the imposition of mandatory in-basin conservation measures and restrictions.
The precipitation Outlook for November to January, issued recently by NOAA, indicates normal conditions across most of the United States. The Southern Plains may receive above‑normal rainfall, and parts of the Southeast below‑normal rainfall. If such conditions were to Occur, the water resources situation in South Carolina, Georgia, and northern Florida could only get worse. However, it is worth noting that we are now entering the time of the year when water demand goes down. Evaporation is reduced, and people will not be watering lawns, washing cars, or irrigating crops as during the summer months. So declines in streams and aquifers will be less noticeable to the average citizen now than in the late spring or summer. Still, normal rainfall would not be sufficient to restore deficient stream‑ and aquifer‑levels to normal. It would take above normal precipitation over a period of weeks to months to do that. Thus, given current hydrologic conditions, the East Coast will need to average above‑normal precipitation over the coming four to five months to ensure that normal water supplies are available next spring and summer; particularly in those areas already experiencing shortages.
The streamgaging network, that measures the "pulse" of the Nation's rivers (and enables LIS to produce a "snapshot" of conditions such as I have used here), is a priority for the USGS. We have worked closely with the Congress over the last 3 years and thanks to your Support, and the support of hundreds of State, local, and tribal agencies, we have made good progress in modernizing and stabilizing the network. We are working with our partners in ail effort to assure that these vital data continue to be available to water resource management.
I should also briefly mention the importance of ground water as an indicator of drought and as ail important aspect of the mechanisms available to communities, agriculture, and industry as insurance against drought. While our ground‑water level monitoring networks have not been modernized to a level where we can provide the same kind of synoptic view of ground‑water conditions as we presented for surface water, we anticipate improvements in the next few years. We believe that the science of groundwater hydrology is crucial to water management not only in and regions, but nationwide. Conjunctive use of surface and ground water has great potential for making water supplies more drought resistant. Ground water is crucial to sustaining streamflow for habitat and for water Supply. More and more we find that our partners are interested in the role that ground water plays in maintaining adequate flow and temperature conditions in rivers.
We also find that emerging technologies such as artificial recharge, aquifer storage and recovery, and recharge of reclaimed wastewater are pivotal parts of the water management equation. The Science to support the use of these new technologies is a part of our strategic plan for the future of USGS ground‑water science.
I thank the Subcommittee for this opportunity to testify and would be pleased to respond to any questions you might have.