Onondaga Lake is adjacent to Syracuse, New York in Onondaga County. Being just northwest of the city of Syracuse, the lake is in the most urbanized area of Central New York. The lake is 4.6 miles long and 1 mile wide, with an average depth of 35 feet.

Unfortunately, Onondaga Lake has been known historically as one of the most polluted lakes in the United States. One of the lakes contaminants is mercury (Hg), which is a very dangerous and toxic chemical. The lake has been contaminated with this chemical since 1946, which has a number of adverse affects. There is an aggressive mercury clean-up effort for Onondaga Lake which is led by Honeywell.