Environmental Engineering Reference
In-Depth Information
the two primary reservoirs, Lake Mead and Lake Powell, which have
gone from nearly full to half-empty since 1999.
7
Some environmentalists
have complained that managing expected population growth was empha-
sized at the expense of conservation measures, but the government
believes the new agreement was the best that could be achieved among
the many competing interests.
The Great Lakes
The Great Lakes contain 6 quadrillion gallons of freshwater, 20 percent
of the world's supply (see fi gure 1.2 and table 1.2). Only the polar ice
caps contain more. However, the Great Lakes supply only 4.2 percent
of America's drinking water, despite the fact that they contain 90 percent
of the nation's freshwater supply. Communities within the Great Lakes'
drainage basin are awash in freshwater, and businesses and residents in
Figure 1.2
Drainage basin of the Great Lakes. (Atlas of Canada)
