toxic metals or nondegradable synthetic organic compounds is a long-term hazard. In this case, arsenic will continue to be a contaminant in the Cheyenne River basin for many years. Great Lakes Water-Use The Great Lakes form the largest volume of unfrozen freshwater in the world (5,000 cubic miles of water) and supply drinking water for 26 million people in the United States and Canada. This international resource is important to the economy and the quality of life of millions of people. One-seventh of the total population of the United States and about one-third of the total population of Canada reside within the Great Lakes basin, and its people and 45° 40° quantity of water. This good-faith agreement calls for equitable decisions between individual States and Provinces to preserve the region's ecological integrity, formulates procedures to determine water-data needs, and establishes communication and cooperative programs among jurisdictions. The Great Lakes Charter mandates collection of water-use data as a prerequisite to dialogue among authorities on the advisability of proposed water-use projects discussed in the context of regional interests. These data are to be stored in the Great Lakes Regional Water-Use Data Base, which was designed by the U.S. Geological Survey as part of a project outlined by the Great Lakes Charter and supported by the Council of Great Lakes Gov ernors. The signing of the Great Lakes Charter authorized formation of the Water Resources Management Committee, which is composed of representatives appointed by the governors and premiers of each Great Lakes State and Province. The Committee was charged with the responsibility of identifying specific common water-data needs; developing and designing a system for the collection and exchange of comparable water-resources-management data; recommending institutional arrangements to facilitate the exchange and maintenance of such information; and developing procedures to implement the prior-notice and consultation process established in this Charter. 50° Figure 12. Major geographic fea tures of the Great Lakes-St. Lawrence River basin. THERMOELECTRIC POWER Figures may not add to totals because of independent rounding ing, and more than 25 percent of its chemical production. Almost 50 percent of the Canadian manufacturing is on the Great Lakes shoreline. Power generation represents the largest demand on water resources within the Great Lakes basin. In 1983, 23.7 billion kilowatt-hours of hydroelectric power were generated in the United States and another 20 billion in Ontario by water flowing through the lakes. The Great Lakes-St. Lawrence Seaway is the world's largest and one of its most important waterways. It is navigable for 2,400 miles, from the Atlantic Ocean to the head of Lake Superior, and is being continually developed and maintained by both the United States and Canada. The withdrawals of water in the United States and Ontario, by major water-use category (fig. 13), are presented only for general comparison. Water that is withdrawn can either be consumed or returned to the hydrologic system. Most of the water withdrawn to cool thermoelectric powerplants is returned, for example, whereas only a small percentage of that withdrawn for irrigation is returned (fig. 14). "Consumptive use" means rendering water unavailable through evaporation, transpiration, incorporation into products, or removal from the water environment by other means. In the U.S. part of the Great Lakes basin (fig. 15), industrial water use, irrigation, and public supply each represent approximately equal amounts of con Figure 14. Percentage of total water withdrawals that are returned in the Great Lakes basin in the United States, 1980, by category. (Data from U.S. Geological Survey Circular 1001, 1983). PERCENTAGE OF WITHDRAWALS RETURNED 100 80 60 40 20 use data. The National Water-Use Information Program was designed by the USGS as a cooperative program between the States and the Federal government to collect, compile, study, store, and publish water-use data. USGS staff in each State work with local and State agencies on that program. IRRIGATION 330 Mgal/d 26.3% Figure 15. Consumptive water use in the Great Lakes basin in the United States, 1980, by category. (Data from U.S. Geological Survey Circular 1001, 1983.) PUBLIC WATER SUPPLY 310 Mgal/d 24.7% Figures may not add to totals because of independent rounding The project chief also held interviews in each State and Province to verify that all appropriate agencies and ministries had been identified and that the data-collection programs were accurately described. A second questionnaire was circulated to obtain a description of how the data are entered in the agencies' computerized-data files. Results From the questionnaires, the USGS researchers learned that the data-collection programs in the participating States and Provinces differ widely in definitions of categories of water use and in methods of estimating data. The most complete datacollection records are in the category of public water supply; the least complete are for hydroelectric power generation and mining. Most agencies can provide estimates of withdrawals in the categories of domestic self-supplied and agricultural, and a few have data-collection programs that document consumptive use. Estimates range from county or drainage basin at 5-year intervals to site-specific data collection yielding daily values. Gaps and inconsistencies in datacollection programs were identified by water-use category for each State and Province, and methods of rectifying them were suggested. Institutional arrangements were suggested as a method for various data-collection activities to complement one another. The Great Lakes Charter mandates, as a goal, that each State and Province be able to supply the information required by the Great Lakes Regional Water-Use Data Base. Much remains to be done in meeting this goal; as of 1987, no State or Province could provide complete records in all water-use categories. Great Lakes Regional Water-Use Data Base The Great Lakes Charter states, in regard to the "common base of data," that "In order to provide accurate information as a basis for future water resources planning and management, each State and Province will establish and maintain a sys tem for the collection of data on major water uses, diversions, and consumptive uses in the Basin." |