Lake Ontario

Lake Ontario is the smallest and most easterly of the five Great Lakes, bounded by Ontario and New York. The Canadian side is densely populated with over nine million people or a quarter of the Canadian population living within its watershed. With the exception of Rochester, New York, the United States shores are mostly rural. Roughly 80% of Lake Ontario's water comes from the Niagara River via Lake Erie and 93% flows out through the St. Lawrence River.

Due to heavy pollution caused by untreated industrial, chemical and untreated sewage runoff, Lake Ontario has been found to contain over 360 identified and many more unidentified chemicals. During the 1960s and 1970s, much of the fish population began to die because of frequent and severe algal blooms. Cleanup efforts, including stricter environmental regulations and improved treatments plants have attempted to restore Lake Ontario with promising initial results.