United States 6,777 Colorado 981 California 363 New York (State) 177 Washington (State) 141 Texas 134 Florida 125 China 123 Great Lakes (North America) 123 Pennsylvania 119 Europe 110 New Jersey 109 Massachusetts 104 Canada 99 Idaho 99 Ohio 92 Alaska 91 Michigan 88 Minnesota 79 Denver Metropolitan Area 78 European Union countries 70 Illinois 70 Great Britain 69 Wisconsin 66 Nevada 63 Wyoming 63 Montana 61 Tennessee 61 Missouri 58 North Carolina 58 Arizona 57 Kansas 56 Maryland 56 Chesapeake Bay (Md. and Va.) 54 Utah 54 Alabama 53 Mexico, Gulf of 53 India 50 North America 50 West (U.S.) 50 Virginia 48 Mexico 47 Indiana 45 Oklahoma 44 Denver 43 Developing countries 43 Oregon 41 Japan 40 Louisiana 40 South Carolina 40 Georgia 39 Iowa 36 New Mexico 36 West Virginia 36 Connecticut 35 Great Lakes Region (North America) 34 Idaho National Laboratory Region 34 Kentucky 34 Arctic regions 31 European Economic Community countries 31 Jefferson County 31 Michigan, Lake 31 Washington (D.C.) 31 New York 30 Chesapeake Bay Watershed 29 Los Angeles 29 Mississippi 29 Asia 27 England 27 Europe, Eastern 27 Middle West 27 Mississippi River 27 Nebraska 26 Erie, Lake 25 Rhode Island 25 San Joaquin Valley 25 New England 24 North Dakota 24 Maine 23 Snake River Plain (Idaho and Or.) 23 South Dakota 23 Soviet Union 22 Front Range (Colo. and Wyo.) 21 Germany 21 Hawaii 21 Atlantic Ocean 20 Australia 20 Cape Cod 20 Great Lakes 20 Ontario 20 Hudson River (N.Y. and N.J.) 19 Mississippi River Watershed 19 Puget Sound 19 Delaware 18 Superior, Lake 18 Animas River Watershed (Colo. and N.M.) 17 Long Island 17 Long Island Sound (N.Y. and Conn.) 17 New Hampshire 17 Southeast Asia 17