Abstract:
Water Resources Regional Reports, consists of separately published reports for each of the 21 regions. Synopses of these reports are given in Volume 2, Part V. For compiling and analyzing water resources data, the Nation has been
divided into 21 major water resources regions and further subdivided into 106
subregions. Eighteen of the regions are within the conterminous United
States; the other three are Alaska, Hawaii, and the Caribbean area.
The 21 water resources regions are hydrologic areas that have either
the drainage area of a major river, such as the Missouri Region, or the
combined drainage areas of a series of rivers, such as the South Atlantic Gulf
Region, which includes a number of southeastern States that have rivers
draining directly into the Atlantic Ocean and the Gulf of Mexico.
The 106 subregions, which are smaller drainage areas, were used exclusively
in the Second National Water Assessment as basic data-collection
units. Subregion data point up problems that are primarily basin wide in
nature. Data aggregated from the subregions portray both regional and
national conditions, and also show the wide contrasts in both regional and
national water sources and uses. The Second National Water Assessment and its data base constitute a major step in the identification and definition of water resources problems by the many State, regional, and Federal institutions involved. However, much of the information in this assessment is general and broad in scope; thus, its application should be viewed in that context, particularly in the area of water quality. Further, the information reflects areas of deficiencies in availability and reliability of data. For these reasons, State, regional, and Federal planners should view the information as indicative, and not the only source to be considered. When policy decisions are to be made, the effects at State, regional, and local levels should be carefully considered. In a national study it is difficult to reflect completely the regional variations within the national aggregation. For example, several regional reviewers did not agree with the national projections made for their regions. These disagreements can be largely attributed either to different assumptions by the regional reviewers or to lack of representation of the national data at the regional level. Therefore, any regional or State resources-management planning effort should consider the State-regional reports developed during phase II and summarized in Volume 4 as well as the nationally consistent data base and the other information presented in this assessment. Additional years of information and experience show that considerable change has occurred since the first assessment was prepared in 1968. The population has not grown at the rate anticipated, and the projections of future water requirements for this second assessment are considerably lower than those made for the first assessment. Also, greater awareness of environmental values, water quality, ground-water overdraft, limitations of available water supplies, and energy concerns are having a dramatic effect on water-resources management. Conservation, reuse, recycling, and weather modification are considerations toward making better use of, or expanding, available supplies.
