Region
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Maryland
13
Montana
13
Utah
13
Australia
12
Iowa
12
Los Angeles
12
Russia (Federation)
12
New York
11
Prince William Sound
11
Puget Sound
11
Appalachian Region
10
Developing countries
10
England
10
European Union countries
10
Great Lakes Region (North America)
10
Louisiana
10
Mexican-American Border Region
10
Mississippi
10
France
9
Gulf of Mexico
9
Maine
9
Navajo Nation, Arizona, New Mexico & Utah
9
New England
9
New Mexico
9
Washington (D.C.)
9
West (U.S.)
9
Antarctica
8
Fukushima-ken
8
Missouri
8
Nebraska
8
North Dakota
8
Oahu
8
Europe, Eastern
7
Germany
7
London
7
Puerto Rico
7
Snake River Plain (Idaho and Or.)
7
Snake River Plain Aquifer
7
Susquehanna River Watershed
7
Animas River Watershed (Colo. and N.M.)
6
Erie, Lake
6
Fort Gordon
6
Fort Gordon (Ga.)
6
Gulf Coast (U.S.)
6
Hudson River (N.Y. and N.J.)
6
Long Island Sound (N.Y. and Conn.)
6
Mississippi River
6
Morris County
6
Ontario
6
Pacific Ocean
6
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