Pollutants & Sources

Phosphorus Ammonia & Nitrite Combined Sewer Overflows Mercury & Other Industrial Wastes Sediment Loading: Tully Valley Mudboils Salinity Nonpoint Source Pollution

Approximately 7 million cubic yards of Onondaga Lake sediments are contaminated with mercury, and mercury has been measured in the flesh of lake fish at levels that exceed federal food standards.

What Is Mercury?

Mercury is a metal that is found in a variety of forms. Methyl mercury, formed in aquatic systems through the activity of certain bacteria, is among the most poisonous chemicals known. If all the mercury in the average fever thermometer were converted to methyl mercury, it would be enough to render more than 10,000 one pound largemouth bass unfit for human consumption. Mercury has been measured in the flesh of fish taken from Onondaga Lake at levels that exceed federal food standards.

Mercury Sources

The Allied chlor-alkali facility discharged an estimated 165,000 pounds of mercury to Onondaga Lake from 1946 until 1970. Mercury loading to the lake was greatly reduced during the period between 1970 and 1988. Scientists estimate that 7 million cubic yards of the lake sediments remain contaminated. As a result, the lake bottom sediments are listed as a hazardous waste site.

The exact source of mercury to the fish in Onondaga Lake is being studied. Scientists are currently investigating the lake's tributaries and sediments to identify why Onondaga Lake fish are still being contaminated. Recent measurements indicate high concentrations of mercury enter the lake from Nine Mile Creek and the Metro wastewater treatment plant.

Fish Consumption Advisory

Mercury was first detected at dangerous levels in fish from Onondaga Lake in 1970. As a result, fishing was banned that same year. Although fishing is now allowed, the New York State Health Department has issued an advisory against eating fish caught from Onondaga Lake and its tributaries because of mercury contamination. Another reason why contamination of the fishery is a problem of great concern, is because contaminated fish migrate freely between the lake and the Seneca River.

Mercury Studies

Allied-Signal, Inc. (Honeywell) is completing a series of mercury studies under the direction of the New York State Departments of Environmental Conservation and Law to identify the major sources of mercury to the lake system and recommend ways to eliminate contamination of the fish.

Other Toxic Substances

Other toxic substances such as PCBs and chlorinated benzenes have also been detected in the lake ecosystem. Mercury, however, remains the contaminant of most concern because of its persistence in the fish found in the lake.

Superfund Designations

In addition to the former Allied facilities and property, the Superfund law is being used to address a number of other contaminated areas in the watershed (see figure below). In December 1994, a collection of sites including the lake bottom were added to the federal Superfund National Priorities List (NPL). In 1995, EPA authorized DEC to conduct a preliminary site investigation of the Onondaga Lake NPL site. The Onondaga Lake NPL site includes a number of smaller sites owned by Allied-Signal (Honeywell) and other potentially responsible parties (PRP). Today, the DEC is evaluating 10 to 15 additional sites that are not owned by Honeywell, to determine if they should be included in the overall Onondaga Lake Superfund site.

Onondaga Lake Superfund Sites