Onondaga Lake Superfund (NPL) Sites - Site Descriptions - Onondaga Lake Bottom Subsite

News/ Documents
pdf documentFact Sheet

pdf documentDraft Onondaga Lake Sediment Consolidation Area (SCA) Civil and Geotechnical Initial Design Submittal (IDS).
December 2009

pdf document
Citizen Participation Plan
for the Onondaga Lake Bottom Subsite Remedial Design Program

March 2009

iconDEC Region 7 Press Release - November 2008

iconAmbient Monitoring Program - Required by State and Federal regulations.
December 2006

iconOnondaga Lake Amended Consent Judgment

iconRecord of Decision
July 2005
Onondaga Lake Bottom Sediments

A sub-site of the Onondaga Lake Superfund Site  

New 2010 Fact Sheet

2010 Brochure Overview

search the EPA for "onondaga lake"

Honeywell's Presentation on Onondaga Lake Mercury.

Superfund Site Progress Profile

Superfund (CERCLIS) Description Report

EPA site overview

Consent Decree Onondaga Lake Bottom Subsite

Consent Decree Fact Sheet

- October 2006

Consent Decree Supporting Documents

Draft Onondaga Lake Dredging, Sediment Management and Water Treatment Initial Design Submittal
May 2009

Onondaga Lake Remedial Design Work Plan - March 2009

Citizen Participation Plan for the Onondaga Lake Bottom Subsite - March 2009

Figure 1. Bird’s-eye view of Onondaga Lake, showing important tributaries, contaminated waste sites, wetlands and landmarks. The view is looking almost due north.
Source: Fig. 1-4, Onondaga Lake Remedial Investigation Report (TAMS and NYSDEC, 2002)


Onondaga Lake, located in metropolitan Syracuse, NY, is a relatively small lake, approximately 4.5 miles long and 1 mile wide, with a mean depth of approximately 38 feet and a maximum depth of approximately 68 feet. Several tributaries flow into the lake, including Onondaga, Ninemile, and Ley Creeks. The Lake drains northerly to the Seneca River which combines with the Oneida River to form the Oswego River, and which in turn empties into Lake Ontario. For many centuries, the lake was home to the Onondaga Nation, one of the six members of the Haudenosaunee (Iroquois) Confederacy.

Today, Onondaga Lake is bordered on its eastern shore by the suburban village of Liverpool, on its northwestern shore by the town of Salina, and on its southwestern shore by the town of Geddes. In the 19th century, salt springs of the lake created a booming salt mining industry that was responsible for the rapid population and economic growth of Syracuse. In the late 1800s and early 1900s, Onondaga Lake supported both thriving recreational resort and commercial fishing industries. However, from the late 1800s to the present, Onondaga Lake has been a receptacle for both industrial and municipal wastes.

Figure 2. Aerial photograph, circa 1960s, shows most of the “Syracuse Works” in Solvay, NY.
 The reservoir in the foreground held brine mined from the Tully Valley, south of Syracuse. The village of Solvay lies to the left, and Solvay wastebeds #7-8 in the upper right. The Main Plant is in the center of the photo. The NYS Fairgrounds and Solvay wastebeds #9-11 lie behind it.

The Solvay Process Company began operations on the shores of Onondaga Lake in 1884. It used the ammonia soda (Solvay) process to produce soda ash, a product used in a variety of applications, including the manufacture of industrial chemicals and glass. This and three other chemical firms merged to become the Allied Chemical & Dye Co. on December 17, 1920. This company shortened its name to Allied Chemical

Corp. in 1958, and to Allied Corp. in 1981.  In 1985, Allied merged with Signal Inc., forming Allied-Signal, which in 1999 merged with Honeywell; the resulting company is known as Honeywell International Inc.
Honeywell and its predecessor companies will be referred to as Allied/Honeywell in these Fact Sheets. Allied/Honeywell operated at four main locations throughout the 102-year existence of the “Syracuse Works.”

Allied/Honeywell plant site

Major Products/Operations


1. Main Plant:

soda ash, related products

1884 – 1986

benzene, toluene, xylenes, and naphthalene

1917 – 1970

coal-fired power plant

1884 – 1986

2. the Willis Avenue plant

chlor-alkali products

1918 – 1977

chlorinated benzenes

1918 – 1977

3. Semet-Solvay-Barrett Div.

coal-derived paving material

1919 – 1983 1

4. Bridge Street plant

chlor-alkali products

1953 – 1979 2

hydrogen peroxide

1956 – 1969

1 This operation was sold to Penn-Can Corporation in 1983, which continues to operate.
2 The Bridge Street plant was sold to LCP in 1979, which operated it until it was shut down in 1988.

Sources of pollution

There were two major sources of industrial pollution from the Allied/Honeywell Syracuse Works:  the East Flume, which led to an 84-acre deposit of contaminated waste known as the “In-Lake Waste Deposit”; and Geddes Brook/Ninemile Creek, which combined overflow from the Solvay waste beds and effluent from the LCP Bridge St. Plant to form another large deposit of material at the mouth of Ninemile Creek. Both deposits are contaminated with mercury and chlorinated benzenes. The In-lake Waste Deposit is also contaminated with BTEX, PCBs, dioxins/furans, other heavy metals, and polyaromatic hydrocarbons (esp. naphthalene).

Other sources of industrial pollution include Ley Creek, which has transported PCBs and other pollutants from General Motors IFG facility, Carrier Corp., and other industries, as well as leakage from the Town of Salina Landfill. These sites are discussed in Fact Sheets #5-7. Bloody Brook, in Liverpool, has apparently contributed cadmium, PCBs and other pollutants from local industries, including the former General Electric facility at Electronics Park. The area immediately to the east of Onondaga Lake, current home of the Carousel Center and a sewage treatment plant, was formerly occupied by dozens of petroleum and chemical storage tanks (“Oil City”), as well as scrap metal yards, coal gasification facilities, and other sources of pollution to Onondaga Creek, which flows into Onondaga Lake.

Industrial contamination of the lake has been compounded by municipal pollution from the Metro sewage treatment plant, which overwhelmed the lake with excess ammonia (toxic to fish) and phosphorus. The phosphous led to rampant algae growth, causing an unpleasant odor and appearance, as well as depriving the lake waters of oxygen. Water quality in the lake has greatly improved as a direct result of major upgrades to the treatment processes at the Metro facility. Ammonia and phosphorus levels are now incompliance with court-mandated target concentrations.

Environmental Degradation

The New York State DEC has determined that contamination in the lake presents risks to many species in the Onondaga Lake ecosystem, including plants, invertebrates, amphibians, fish, birds, and mammals. Chemical contamination of the sediments is severe enough to be highly toxic to benthic (bottom-dwelling) organisms. It is suspected that chemical contamination has diminished the local frog population. In addition to chemical toxicity, both plant and animal life has been greatly affect by loss of habitat through the filling in of wetlands with Solvay waste and other materials, the deposition of huge quantities of calcium carbonate on the bottom of Onondaga Lake, and general urban, suburban, and industrial development. These issues are discussed in detail in the Baseline Ecological Risk Assessment (TAMS and NYSDEC, 2002).

Human Health Risks

The major health risks associated with Onondaga Lake itself (not including upland sub-sites) are due to fish consumption and direct contact with some of the sediments and soils near the lake. Contact with the waters of Onondaga Lake poses littel to no risk.
A Human Health Risk Assessment published by NYSDEC in 2002 revealed that exposure to wetland soils and lake sediments resulted in unacceptably high cancer risks. Sediments are contaminated with polychlorinated biphenyls (PCBs); pesticides; creosotes; heavy metals, including lead, cobalt, cadmium, and mercury; polycyclic aromatic hydrocarbons; and volatile organic compounds such and chlorobenzene, benzene, and toluene. In addition, consumption of fish resulted in unacceptable cancer and non-cancer risks.  Non-cancer risks arise from mercury, which is a neurotoxin, and PCBs.

Mercury in Onondaga Lake Fish

A ban was placed on public fishing from the lake in 1970 due to high concentrations of mercury in several species of fish. The lake was re-opened to fishing in 1986 on a catch and release basis only. Currently, the New York State Department of Health advises men to limit consumption of certain species of fish from the lake and its tributaries, while women and children are advised not to consume any fish at all. These advisories are based high concentrations of mercury, chlorinated dioxins/furans, and PCBs found in the fish.

Figure 3. The graph above shows 24 years’ worth of mercury data for smallmouth bass caught in Onondaga Lake. The red line shows the median mercury concentration in fish fillets: half of the fish had greater mercury values, and half had smaller mercury values. (Typically, 40-50 fish are caught and tested each year.)

Figure 3 shows mercury concentrations in a sportfish (sm.bass) over the period 1981 to 2005. For reference, the graph shows a guideline set by the US Food & Drug Administration (FDA) for commercial fish. The 1-ppm guideline was set in 1979, and has remained unchanged ever since. The USEPA’s Office of Science and Technology established a guideline (also shown) of 0.3 ppm based on eating one meal per week. Health Canada’s guideline is 0.5ppm.  In any case, two things are clear:
1) A large fraction of sm. bass caught in Onondaga Lake are above all of the guidelines. In 15 of the 24 years shown at least 50% of the fish are above the FDA guideline. In nearly all years, all of the fish are above the guideline, up to a factor of ten above.
2) the concentration of mercury is not decreasing. Recent years have even seen an increase, despite reductions in the amount of mercury entering the lake. The recent upward trend in mercury in fish remains unexplained.

A major goal of the remedial actions being undertaken in Onondaga Lake is to reduce the level of mercury contamination in the lake’s fish. It is uncertain that this goal can be achieved.

Figure 3 Key: The wide blue box shows the most common mercury levels, while the blue lines show the complete range of mercury levels in a given year.

Other chemicals, such as hexachlorobenzene and pesticides, contribute to the overall risk, but to a much lesser degree.

Defined as males over the age of 16.

“of child-bearing age.”



Figure 1. Mercury concentrations in the top 12-inches of sediment in Onondaga Lake. The black line is the 9-m (30-ft) depth contour. Sediments inside this line will not be dredged. A small fraction will receive a thin cap.

Figure 2. Total dichlorobenzene levels in the top 12-inches of sediment in Onondaga Lake. Concentrations are expressed as “toxicity equivalents;” a value of 1 is at the threshold of toxicity to bottom-dwelling organisms. Areas in dark blue are non-toxic, while light blue, green, yellow, etc. represent increasing levels of toxicity. The white line is the 9-m (30-ft) depth contour.

1. mercury in sediments
2. dichlorobenzenes in sediments

Description and Environmental Issues

Onondaga Lake, located in metropolitan Syracuse, NY, has suffered from many years of industrial pollution, from multiple sources, and from sewage pollution. See Fact Sheet #1A for a more detailed description and historical overview. As a result of over 100 years of industrial pollution, the sediments of the lake are contaminated with a long list of chemicals, most notably mercury, polychlorinated biphenyls (PCBs), chlorinated benzenes, and polyaromatic hydrocarbons (PAHs). Major sources of these pollutants include the Allied/Honeywell chemical complex on the southern shore of the lake, various industries and landfills in the Towns of Salina (e.g. General Motors IFG plant and Electronics Park) and Dewitt, and the city of Syracuse (e.g. petroluem storage center known as “Oil City).

Figures 1a and 1b show the distribution of mercury and dichlorobenzenes in the top sediments of Onondaga Lake. Both of these contaminants were primarily from the Allied/Honeywell chemical complex (see FS#1A for details). These compounds are problematic because they are toxic to organisms that live on the bottom of the lake, and which serve as a source of food to many species of fish in the lake. Certain chemicals, including mercury, PCBs, dioxin, and hexachlorobenzene also pose a threat to human health and wildlife because they bioaccumulate in fish, leading to levels that are unsafe to eat.

What's being done to address the problem?

A proposed plan for the lake sediments was released to the public in late 2004. In the plan, the lake was divided into eight “Sediment Management Units” (SMUs) as shown in Figure Y.

After extensive public comment, and internal review, a Record of Decision for the Onondaga Lake Bottom sub-site was issued by the NYSDEC and the EPA on July 1, 2005. The selected remedy includes:

1) Littoral zone = nearshore areas (water depths up to 30 feet): Up to 2.65 million cubic yards of contaminated sediments are to be hydraulically dredged, and disposed of in an area of Wastebed 13 designated as the  Sediment Consolidation Area (SCA) (see Figure X). An estimated 425 acres would be covered with a 4-ft thick “isolation cap” consisting of sand and topped with gravel. Much of this area would also be restored with native aquatic plants.

2) profundal zone  = central part of the lake (water depths exceeding 30 feet)  thin layer capping of an estimated 154 acres. Most of the profundal zone will be left untouched, allowing clean sediments to cover over the contamination. This is called “monitored natural recovery.”

The most highly contaminated sediments—a small fraction of the total— would likely be disposed of off-site.  Wastewater generated by the dredging/sediment handling processes as a result of dewatering of the sediments at the SCA would be treated prior to being discharged back to the lake.
The estimated cost to implement the remedy is approximately $451 million, which includes $414 million to construct the remedy, and the average operation and maintenance cost of about $3 million per year for 30 years.

Recent findings by Honeywell have led to changes in the amount of dredging to take place in the southwest portion of the lake (SMU#2). The change is necessary to ensure the stability of the adjacent causeway and the adjacent area which includes a portion of I-690, and is supported by recent, more extensive sampling of the area which indicates that the pure chemical contamination is significantly less extensive than previously estimated. A Consent Decree related to the performed of the design and construction of the remedy by Honeywell under New York State oversight was entered in federal district court in January 2007. Pre-design related activities are currently underway

Documented in Explanation of Significant Difference (ESD), dated December 2006.

Map showing placement of barrier wall along lakeshore, sediment pipeline, and SCA on Wastebed 13.


Contacts for more information and comments

Timothy Larson, Project Manager tjlarson@gw.dec.state.ny.us                     518-402-9676
New York State Department of Environmental Conservation
625 Broadway, 12th floor
Albany, NY 12233-7016

Mark Sergott, Project Manager beei@health.state.ny.us                                800-458-1158 Ext. 27860
New York State Department of Health
547 River St
Troy, New York 12180-2216

Documents for this site are available for public inspection at:
Atlantic States Legal Foundation Depository Library
658 West Onondaga Street, Syracuse NY 13204-3711                                                              
 Phone: 315-475-1170 http://www.aslf.org/

Onondaga County Public Library
Central Branch at the Galleries
447 South Salina Street, Syracuse, NY 13202                                                                        
Phone: (315) 435-1800
Hours: M, Th, Fri, Sat, 9:00 a.m. - 5:00 p.m.; Tu, W, 9:00 a.m. - 8:30 p.m.

New York State Department of Environmental Conservation
625 Broadway, Albany, NY 12233-7016                                                                                          
Phone: (518) 402-9676
Hours: M - Fri, 8:30 a.m. - 4:45 p.m. Please call for an appointment

Fact Sheet for Remedial Design Work Plan and Citizen Participation Plan for the Onondaga Lake Bottom

March 2009

Onondaga Lake Bottom Site Fact Sheet - July 2005

Record of Decision Issued for the Onondaga Lake Bottom Site

Original Amended Consent Judgement

Concurrence Letter from DOH to DEC

The New York State Department of Environmental Conservation (NYSDEC) and the United States Environmental Protection Agency (EPA), in cooperation with the New York State Department of Health, have issued the Record of Decision (ROD) for the Onondaga Lake Bottom site, a subsite to the Onondaga Lake National Priorities List Site. The ROD, which documents the selected remedy for the site, was signed on July 1, 2005. The ROD includes a Responsiveness Summary which responds to the comments received during the public review process.

This fact sheet highlights the Record of Decision and provides site background information, as well as contact information should you desire additional information.

Related local news:

Honeywell plans to dredge and bury Onondaga Lake sediments

Honeywell plans to dredge and bury Onondaga Lake sediments

A hydraulic dredger like this one is part of Honeywell's plan to
pull contaminated sediments from the floor of Onondaga Lake.

Atlantic States Legal Foundation, the Syracuse group which filed a lawsuit in the 1980s to force Onondaga County to stop polluting the lake with sewage, is among those advocating for a different dredging plan.

Samuel Sage, president of Atlantic States, said the group would like to see the dredged sediment cleaned and returned to the lake, rather than buried in Camillus.

Photo Courtesy of Honeywell

Elements of the Remedysampling at the lakeside

Key elements of the Record of Decision include:

  1. Dredging of as much as an estimated 2,653,000 cubic yards of contaminated sediment/waste from the lake.
  2. Placement of an isolation cap over an estimated 425 acres of the shallower portion (where water depths are less than 30 feet)of the lake bottom.
  3. Placement of a thin-layer cap over an estimated 154 acres of the deeper portion (where water depths are greater than 30 feet) of the lake bottom.
  4. Construction/operation of a hydraulic control system along the SMU 7 shoreline to maintain cap effectiveness.
  5. Treatment and/or off-site disposal of the most highly - contaminated materials (e.g., pure phase chemicals segregated during the dredging/handling process). The balance of the dredged materials will be placed in one or more Sediment Consolidation Areas (SCAs), which will be constructed on one or more of Honeywell's Solvay wastebeds that historically received process wastes from Honeywell's former operations.
  6. Treatment of water generated by the dredging and sediment handling processes to meet NYSDEC discharge limits.

    watershed for onondaga lake

  7. An oxygenation pilot study in the deeper portion of the lake to reduce mercury methylation and dissolved mercury concentrations. This study will be followed by full-scale oxygenation if supported by the pilot study.
  8. The monitoring of the natural covering of the contaminated sediments with clean sediments (Monitored Natural Recovery) discharged from tributaries to the lake.
  9. Completion of a comprehensive lakewide habitat restoration plan.
  10. Habitat reestablishment in areas where dredging/capping will occur.
  11. Habitat enhancement along an estimated 1.5 miles of shoreline and over approximately 23 acres to stabilize deposits and promote submerged macrophyte growth.
  12. Implementation of institutional controls including the notification of appropriate government agencies with authority for permitting potential future activities which could impact the implementation and effectiveness of the remedy.
  13. Implementation of a long-term operation, maintenance, and monitoring (OM&M) program to monitor and maintain the effectiveness of the remedy.
  14. The control of contamination migrating to the lake from the various upland sites is an integral part of the overall cleanup of Onondaga Lake. The timing of remedial activities in Onondaga Lake will need to be coordinated with the remedial work which will be performed as part of the remedies at the upland sites.
  15. Collection of additional data needed for design of the remedy.

The cost to implement this remedy is estimated at $451 million with a three-year design and a four-year construction period.