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Onondaga Lake Superfund Site

Lake Size and Depth

The lake covers an area of 4.6 square miles, has an average depth of 35 feet and a maximum depth of 63 feet. Its volume is about 35 billion gallons. It is approximately one mile wide and 4.6 miles long, and receives water from a land area, or drainage basin, of 248 square miles located almost entirely within Onondaga County, New York.

Historical Background

The Onondaga Lake area was the center of the Iroquois Confederacy prior to the exploration and settlement by Europeans. The completion of the Erie Canal in the early 1800's led to increased settlement of the area. Many early settlers were attracted to the Syracuse area because of the newly developing salt industry on the Lake's shores. Increased population and the industrialization resulted in pollution that degraded water quality and severely impacted lake use and related industries.

History of Pollution

Onondaga Lake has been described as one of the most polluted lakes in the United States. The lake has a number of domestic and industrial pollution problems relating to population growth and industrialization in Syracuse over the last century. As Syracuse grew in the late 19th and the early 20th century, the lake's western shore became increasingly industrialized. Sewage disposal and industrial discharges into the lake also increased during this period, and as a result, the quality of the water began to suffer. Eventually, people stopped visiting Onondaga Lake for swimming and fishing, primarily because of the lake's degraded water quality. Over time, all of the lake's resorts and beaches closed. By World War II, the lake was mainly being used for the disposal of industrial and domestic wastes.

There were many sources of pollution to Onondaga Lake. For years the city of Syracuse dumped its sewage directly into the lake. This municipal wastewater released phosphorus, ammonia and nitrite, bacteria and other harmful microorganisms into the lake. Besides these heavy pollutants the lake began to suffer from a reduced oxygen level which seriously impacted the entire ecosystem of the lake.

In 1884 the Solvay Process Company began the production of soda ash on the western shores of Onondaga Lake. Salty wastes, a bi-product of the soda ash production, were deposited in the lake resulting in a drastic increase in chloride, sodium and calcium. It's estimated that millions of gallons of these wastes were deposited each day. Besides the chemical contamination of the lake, the salinity level rose significantly and dissolved oxygen levels dropped drastically.

Allied Chemical and Dye Company (now Honeywell Corporation) succeeded the Solvay Process Company. It produced chlorine by the chloralkali process, which included the use of mercury cells. The process resulted in the release of mercury to the lake. It's estimated that between 1956 and 1970 165,000 pounds of mercury were deposited in the lake from this production process.

Other companies added to the pollution (including PCBs) in the lake. Finally, the lake also suffers from excessive sedimentation, a problem that is indirectly attributed to the actions of solution mining by Allied Chemical Company.

Cleaning Up the Lake

Cleanup of Onondaga Lake began in the early 1970's with the 1972 passage of the Clean Water Act. The Act required that all the State's fresh waters should be suitable for swimming and the propagation of fish and other aquatic life. Other action in the 1970's included:

  • The county and the state banned the use of phosphorus in laundry detergents
  • A lawsuit was filed against Allied Chemical Corporation to stop mercury dumping
  • An upgrade occurred at the Syracuse solid waste treatment plant (METRO) to improve sewage treatment
  • Allied Chemical Corporation's chlorinated benzene and Willis Avenue chlor-alkali plants were closed
  • Studies were conducted on the impacts of industrial wastes, combined sewer overflows and treated sewage

Action continued in the 1980's with the following major accomplishments:

  • Use of best management practices for sewer interception which reduced combined sewer overflow events by 90%
  • Filing of a complaint against the Onondaga County Department of Drainage and Sanitation by the New York State Department of Environmental Conservation, the New York State Attorney General and the Atlantic States Legal Foundation alleging violation of state discharge permit
  • Filing of a complaint by the New York State Department of Environmental Conservation and the New York State Attorney General against Allied-Signal Inc. alleging pollution violation and resource damage
  • Industrial pre-treatment program instituted by the County
  • Closure of Allied Corporation's soda ash facility
  • Catch and release fishing reinstatement
  • Closure of LCP-Hanlin's Bridge Street chlor-alkali plant.

Further successes occurred in the 1990's including the following:

  • Creation of a "Plan for Action" for the Lake written by the newly established Onondaga Lake Management Conference, a group consisting of representatives from local, state and federal governments
  • Signing of the Amended Consent Judgement by Onondaga County, which requires the County to upgrade existing sewage treatment system and construct facilities and transport system to comply with permit discharge limits and water quality standards
  • Modifications to pump station at Liverpool and Ley Creek to eliminate raw sewage overflows
  • Completion of the Onondaga Lake Water Quality Technical Report by the U.S. Army Crops of Engineers
  • Commencement of aquatic habitat restoration projects in Onondaga Lake
  • Research and remediation projects by the Onondaga Lake Management Conference
  • Completion of mudboil remediation projects to reduce flow of sedimentation to Onondaga Creek
  • Lifting of a ban on eating certain species of fish from Onondaga Lake

Current Status

Due to many of the projects cited above, the water quality and the overall health of Onondaga Lake is improving. The past several years have seen a dramatic decrease in ammonia levels in the lake. This is directly related to improvements made at the METRO wastewater treatment plant which contributes 90% of the lakes's ammonia. Slightly more than half of the phosphorus entering the lake comes from the METRO plant; the other half is contributed by runoff from urban and agricultural areas. Phosphorus levels in the lake are declining as well, but they still remain above the guidance value of 20 micrograms per liter. Dissolved oxygen level and water clarity in Onondaga Lake are improving, in part due to the reduction in phosphorus levels in the lake. Bacteria levels in the lake are still unacceptable for water contact recreation. Thus, continuous improvements in reducing the number of combined sewer overflows (CSOs) are needed. The concentration of chloride, the most important component of salinity to Onondaga Lake has decreased from 1600 milligrams per liter to less than 400 milligrams per liter since the closure of he Allied soda ash facility. The Lake's entire bottom sediments and related upland sites are on the federal Superfund list and the New York State Registry of Inactive Hazardous Waste Disposal Sites. The plan for cleaning up the lake bottom selected by NYSDEC and USEPA in July 2005, can be found at the DEC's website

Detailed historical information about Onondaga Lake's restoration process can be found on the Onondaga Lake Partnership's (OLP) website. Detailed information about the Onondaga Lake Superfund Site, including fact sheets and the Onondaga Lake Record of Decision can be found at the links shown below.

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