Region
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Virginia
62
Michigan
61
Mexico
60
South Dakota
60
Illinois
58
Gulf of Mexico
56
North Dakota
56
Missouri
53
Southern States
53
Colorado River Watershed
50
Kentucky
50
Gulf Coast
49
Hudson Bay
49
Northwest, Pacific
48
Oklahoma
47
Columbia River
46
Colombia
44
Canada
43
East Asia
42
Indiana
42
Connecticut
41
Developing countries
40
Mississippi River
39
Snake River Watershed (Wyo.-Wash.)
39
South China Sea
39
Mississippi
38
Europe
37
Everglades
37
Puerto Rico
37
Central Valley (Valley)
36
San Joaquin Valley
36
Maryland
35
West Virginia
35
Alabama
34
Australia
33
Middle West
33
South Carolina
32
Tennessee River Watershed
32
Middle East
31
Chesapeake Bay (Md. and Va.)
30
Iowa
30
New York
30
Southwest, New
30
Gulf States
29
Pacific Coast (U.S.)
28
Africa
27
Floridan Aquifer
27
Maine
27
Navajo Nation, Arizona, New Mexico & Utah
27
Long Island
26
more ...