Onondaga Lake

Overview

Onondaga Lake sits in Syracuse, New York and carries more than 100 years of industrial and municipal sewage pollution. The EPA added it to the Superfund National Priorities List in December 1994. The site is divided into 29 or 30 operable units covering the lake bottom, creek systems, landfills, industrial properties, and groundwater. Remedial investigation began in June 1989, and active cleanup work started in July 1999. The site has not been deleted from the National Priorities List, and sitewide readiness for reuse has not yet been achieved.

Contamination is widespread across multiple media. The EPA has identified more than 400 chemical substances of concern, including mercury, PCBs, arsenic, lead, cadmium, chromium, and volatile organic compounds such as benzene and vinyl chloride. Mercury is especially widespread, appearing in fish tissue, sediment, soil, groundwater, and surface water. Because of high mercury levels, public fishing was banned in 1970. A fish consumption advisory remains in place today. It prohibits eating largemouth bass, smallmouth bass over 15 inches, walleye, carp, channel catfish, and white perch. Women under 50 and children under 15 are advised not to eat any fish from the lake. Honeywell International and its predecessor companies, which operated chemical facilities on the west shore starting a mercury cell process in 1946, are among the responsible parties for cleanup.

Major cleanup work has been completed at several subsites. Honeywell removed about 2.2 million cubic yards of contaminated sediment from the lake bottom between 2012 and 2014, then capped the area with over three million cubic yards of sand, activated carbon, and other materials, finishing in 2016. Habitat restoration wrapped up in late 2017, and that subsite moved into operation and maintenance in September 2019. The Semet Residue Ponds finished remedial action by June 2020, and the Wastebed B/Harbor Brook subsite completed cleanup in 2022. Soil covers at Wastebeds 1-8 were installed by 2022.

Several areas are still active. The Willis Avenue subsite began remedial action in October 2021 and is undergoing a treatability study for in-place mercury treatment. The General Motors Inland Fisher Guide subsite has a design plan approved in May 2024, with $23 million in federal funding and $7 million from a bankruptcy settlement supporting cleanup expected to start in spring 2027 and take three to four years. The Lower Ley Creek unit is in remedial design with estimated completion around September 2027. The most recent five-year review was completed in February 2026.

Community members can contact EPA's Community Involvement Coordinator. Site records are available at several local locations, including the Onondaga County Public Library and Liverpool Public Library in the Syracuse area, as well as the New York State Department of Environmental Conservation offices.