The United States has about 250 fresh-water lakes that are known to have surface areas of 10 square miles or more. Nearly 100 of these are in Alaska, and 100 in Minnesota, Wisconsin, Michigan, New York,. and Maine. Thirty-four fresh-water lakes, exclusive of the Great Lakes, are known to have maximum depths of 250 feet or more. Twenty of these are in Alaska, and Alaska undoubtedly has more lakes of that depth which have not been sounded.
The amount of water stored in natural lakes--even exclusive of the Great Lakes--is much greater than the amount stored in artificial reservoirs. With the exception of the Great Lakes, however, the economic value of natural lakes is surpassed by that of artificial reservoirs. Natural lakes are best known for the recreational advantages they afford.