Onondaga Lake

Onondaga Lake is a lake in Central New York located northwest of Syracuse, New York. The southeastern end of the lake and the southwestern shore abut industrial areas and expressways; the northeastern shore and northwestern end border a series of parks and museums. Although it is near the Finger Lakes region, it is not traditionally counted as one of the Finger Lakes. Onondaga Lake is a dimictic lake, meaning that the lake water completely mixes from top to bottom twice a year. The lake is 4.6 miles long and 1 mile wide. The maximum depth of the lake is 63 feet with an average depth of 35 feet. Onondaga Lake has a surface area of 12 square kilometers. Its drainage basin has a surface area of 642 square kilometers, encompassing Syracuse, Onondaga County except the eastern and northern edges, the southeastern corner of Cayuga County and the Onondaga Nation Territory, and supports approximately 450,000 people.

Onondaga Lake has two natural tributaries that contribute approximately 70% of the total water flow to the lake. These tributaries are: Ninemile Creek and Onondaga Creek. The Metropolitan Syracuse Wastewater Treatment Plant (METRO) contributes 20% of the annual flow. No other lake in the United States receives as much of its inflow as treated wastewater. The other tributaries, which include Ley Creek, Bloody Brook, Harbor Brook, Sawmill Creek, Tributary 5A, and East Flume, contribute the remaining 10% of water flow into the lake. The tributaries flush the lake out about four times a year. Onondaga Lake is flushed much more rapidly than most other lakes. The lake flows to the northwest and discharges into Seneca River which combines with the Oneida River to form the Oswego River, and ultimately ends up in Lake Ontario.

During the late 19th century many resorts were built along Onondaga Lake's shoreline. However, after the Industrial Revolution domestic and industrial waste, due to development and urbanization, led to the severe degradation of the lake. Unsafe levels of pollution led to the banning of ice harvesting in 1901. In 1940 swimming was banned and in 1970 fishing was banned due to mercury contamination. Mercury pollution is still an existing problem for the lake today. Despite the passage of the Clean Water Act in 1973 and the closing of the major industrial polluter in 1986, Onondaga Lake is still one of the most polluted lakes in the United States. Several initiatives, including a 15-year multi-stage program currently under way, have been recently undertaken to clean up the lake.