Toxic Substances

The Problem

Toxic substances include both naturally occurring and man-made substances that can cause adverse ecosystem or human health risks when exceeding certain concentrations. The Management Conference has reviewed all available data on the levels of toxic substances in the water, biota, and sediments of Long Island Sound. These levels were compared to applicable standards, criteria, and guidelines to provide an indication of environmental problems.

Overall, the quality of Long Island Sound’s waters is good with respect to toxic substances. The only documented case of levels exceeding either state’s water quality standards in the open waters of Long Island Sound is for mercury in the East River. However, data on organic toxic substances (such as polychlorinated biphenyls [PCBs]) were too sparse to allow the Management Conference to draw any conclusions about contamination. While few tests of water column toxicity have been conducted, indications of some aquatic life impairments have been observed in the upper East River.

Analysis of fish and shellfish tissue data indicates that very few contamination problems exist that could affect the health of seafood consumers. The only documented substances of concern are PCBs, most of which were discharged into the environment before the complete ban on their manufacture and severe restrictions on their use. PCB action levels (the minimum concentrations of chemicals in food that may cause the Food and Drug Administration to take enforcement action) are exceeded in the flesh of striped bass, bluefish, eels, and the hepatopancreas (more commonly known as the tomalley) of lobsters and crabs. The states of Connecticut and New York have issued consumption advisories for those species. Because PCBs are globally distributed and most fish and forage species migrate widely, it is not clear if the problem observed in Long Island Sound is caused by local sources.

There are also some concerns about contaminant levels in waterfowl tissues. New York state has issued an advisory on consumption of mergansers and some other waterfowl. The relationship between waterfowl contamination and Long Island Sound management needs is unclear because of the diversity of habitats and wide migration patterns of waterfowl. Connecticut has funded research into contamination of the greater scaup (a diving duck) that may provide additional insight into this type of problem and management needs for Long Island Sound.

Surveys of mussels and oysters, while spatially limited in scope, have identified a few areas where the concentrations of heavy metals and organic compounds in tissues are elevated relative to cleaner sites. These include the urban harbors of Bridgeport, Mamaroneck, and Hempstead, the lower Housatonic River near Devon, and the area around Throgs Neck. While the levels of contamination may affect the health of those species, there are no human health risk/consumption advisories as a result of toxic substances in these organisms.

Sublethal toxic effects on the pathology and reproductive success of organisms have been measured at some locations as well, specifically in flounder in New Haven Harbor and clams in Bridgeport and Norwalk Harbors.

In contrast to the generally low concentrations of toxic substances in the water, toxic contamination problems persist in the sediments of some areas of the Sound. This may be due, in large part, to historical discharges that occurred prior to implementation of state and federal Clean Water Act requirements. Despite the great strides in reducing the load of toxic substances to the Sound, field studies have not documented decreases in the amount of toxic substances in sediments in contaminated areas over time. The database since 1972, for example, does not identify general trends in sediment concentrations of heavy metals. This is probably a function of the slow sedimentation rate in the Sound combined with mixing of the sediments by burrowing organisms. More time is needed for the benefits of source reductions to be observed in the sediments because of these physical and biological attributes of the Sound.

While most of the Sound’s sediments do not exhibit contamination levels of concern, problems have been documented in some areas of the western Sound and in several, mostly urbanized, harbors, rivers, and embayments. In these areas, preliminary data indicate that elevated levels of metals in the sediment could be affecting benthic organisms. Sediments with elevated levels of metals and organic compounds are found in portions of Black Rock Harbor, Bridgeport Harbor, Stamford Harbor, the Quinnipiac River and New Haven Harbor, the Housatonic River, the Five Mile River, the West River, Glen Cove Creek, and the Hutchinson River. Sediments from sites in western Long Island Sound and in urban harbors have also elicited toxic responses in tests using sensitive species.

Overall, the Management Conference has concluded that problems due to toxic contaminants occur in limited areas and are primarily associated with sediment contaminant levels. However, additional data on toxic substances in water, biota, and sediments are essential to a full characterization of the nature and extent of the toxic substance problems in the Sound.

Causes of the Problem

As discussed above, the sediment contamination problems that persist today may be due, in large part, to historical discharges of toxic contaminants. Active industrial and municipal sources of toxic substances still exist but have been greatly reduced. This is the result of the emphasis placed on toxic contaminant control in existing regulatory discharge permitting programs over the last 25 years. Currently, no single source category of toxic substances appears to be the primary determinant of conditions in the Sound. The results of the National Coastal Pollutant Discharge Inventory for the Sound, compiled by the National Oceanic and Atmospheric Administration for the Management Conference, indicate the following relative source contributions of some toxic substances to the Sound:

  • The largest sources of heavy metals are the major rivers that flow into the Sound (Connecticut, Housatonic, Quinnipiac, and Thames), which dominate the total load because of their large discharge volumes. Some of the load originates from natural sources and ambient concentrations of most pollutants do not exceed state criteria for surface waters.
  • Sewage treatment plants in Connecticut and New York are the second largest source of toxic substances and are dominated by the New York City plants.
  • Urban runoff, combined sewer overflows, and stormwater discharges are the third most significant source of toxic substances. They are potentially significant sources of some toxic substances, such as lead, PCBs, and polynuclear aromatic hydrocarbons, and may locally affect Long Island Sound’s waters and biota.
  • Atmospheric deposition may also contribute substantial amounts of some metals, such as copper, lead, and zinc, as well as organic compounds, but additional evaluation is warranted.
  • Relatively minor sources of toxic substances, which may affect limited areas, include: industrial discharges (most notably along the Quinnipiac and Naugatuck Rivers), power plants, old landfills, chemical and oil spills, and boating operations.

The Plan to Solve the Problem

To protect and restore Long Island Sound from the adverse effects of toxic substances, the Management Conference recommends actions in four key areas:

  • Continue and, where appropriate, enhance existing regulatory and pollution prevention programs to reduce toxic substance inputs to Long Island Sound;
  • Further evaluate sediments where toxic contamination problems exist to determine the feasibility of remediation;
  • Improve communication to the public of any legitimate health risks from consumption of seafood species from the Sound; and
  • Coordinate and strengthen monitoring activities for toxic substances to improve understanding and management of toxic contamination problems.

Existing Regulatory and Pollution Prevention Programs

Permit programs and enforcement activity for both direct and indirect discharges, including toxicity testing of those discharges, are responsible for greatly reducing toxic substance loads over the past 25 years. The Management Conference’s priority management recommendation for toxic substances is to continue these successful activities, all of which are funded under current programs.

  • The states of Connecticut and New York are reviewing municipal and industrial discharge permits to surface waters to reduce the allowable concentrations of toxic pollutants from the previous, permitted values. This includes municipal discharges and, therefore, affects pretreated industrial discharges as well. The net result will be a substantial reduction in the discharge of toxic materials over the next few years to meet adopted criteria for toxic substances in the states’ waters.
  • The Management Conference recommends continued support for existing pollution prevention site visit programs targeting industrial dischargers to Long Island Sound and its tributaries. The Connecticut Technical Assistance Program solicits requests from manufacturing facilities for voluntary pollution prevention audits and has conducted more than 40 audits in the past two years. The NYSDEC, as a part of its compliance inspection program, performs multimedia pollution prevention field assessments at sites where permitted activities are taking place.

Other programs that are designed to prevent pollution, reduce pollutant loads, or clean up existing problems and spills must also be supported as part of a comprehensive program to manage toxic contamination in Long Island Sound.

Planned activities under the auspices of the New York-New Jersey Harbor Estuary Program that will enhance toxic substance management in Long Island Sound are:

  • Develop Total Maximum Daily Loads, Waste Load Allocations for point sources, and Load Allocations for nonpoint sources to ensure that water quality standards for mercury are met in the Harbor, the East River, and western Long Island Sound. The Waste Load Allocations and Load Allocations will be completed in 1994. Initially, permits will limit point source discharges of mercury to existing effluent limits.
  • Continue work to fully account for nonpoint sources of mercury, since the work to date has revealed the presence of a major, unidentified nonpoint source of mercury. This additional work is described under Monitoring.

Sediment Contamination

  • The Management Conference will review the data on sediment contamination on a site-by-site basis. State and federal experts will evaluate the problem at each site and recommend additional assessments needed to fully characterize the problem, ascertain the need for and feasibility of remediation, and prepare a remediation plan.
  • Additional assessments should be conducted and site plans addressing the feasibility, technical approach, cost, and value of conducting sediment remediation projects should be developed for Black Rock Harbor and Glen Cove Creek, where data may be sufficient to construct case study analyses. The cost of conducting characterization and feasibility studies is approximately $250,000 per harbor. This translates to $500,000 per year to address the problem at a rate of two harbors per year. Recently, the City of Glen Cove was awarded $250,000 from the New York State Legislature to evaluate the contamination of Glen Cove Creek. Funds for additional evaluations are presently not available.
  • The Management Conference will evaluate the research and management programs and activities in the Great Lakes and New York-New Jersey Harbor as part of developing an approach to remediate sediments. This will ensure cost-effective transfer of appropriate technology to Long Island Sound contamination problems.

Risk Communication

The states of Connecticut and New York will improve the coordination of health risk assessment and advisory recommendations. This will help minimize confusion about the safety of Long Island Sound fish, shellfish, and waterfowl, thus minimizing human exposure to contaminated species.


The Management Conference recommends that a comprehensive, coordinated monitoring program be implemented to fully evaluate toxic contamination problems and their causes and trends in the Sound. Elements of the program include:

  • The National Oceanic and Atmospheric Administration’s Mussel Watch and Benthic Surveillance components of their Status and Trends Program.
  • The EPA’s Environmental Monitoring and Assessment Program, which has stations throughout Long Island Sound, and its Regional Environmental Monitoring and Assessment Program (R-EMAP), which is focusing on sediment contamination in western Long Island Sound as part of a regionwide program. The incremental cost to include Long Island Sound in the R-EMAP program was $200,000.
  • Incorporation of the results of the National Oceanic and Atmospheric Administration’s urban harbor sediment assessment, identifying the need for further assessment.
  • Implementation of a comprehensive monitoring program for toxic substances in edible fish and shellfish to ensure compliance with the newly proposed Food and Drug Administration’s fish safety initiative. The cost of implementing this recommendation is $300,000 per year.
  • Implementing the recommendations of the Management Conference Monitoring Workshop to improve monitoring of toxic substances. The cost of implementing the recommendations is $15,000 per year.
    • The US Army Corps of Engineers has agreed to develop a work plan and budget to complete these models.
    • The Corps and the other New York-New Jersey Harbor Estuary Program Management Conference participants have agreed to seek the funding necessary to complete these models.
    • The systemwide models for PCBs and mercury would provide the technical foundation for comprehensive efforts to eliminate contamination problems in the Sound-Harbor-Bight system.
  • In addition to these general monitoring recommendations, the New York-New Jersey Harbor Estuary Program has drafted a scope of work to develop comprehensive, systemwide models of PCBs, mercury, and other toxic pollutants. The Management Conference endorses these activities that will benefit Long Island Sound. Specific actions include:


The benefits of implementing the plan will be significant.

  • Preventing toxic substances from entering the Sound by continuing successful regulatory and pollution prevention programs is the most effective method of preventing future degradation and, in many instances, may be the most economical means of managing toxic substances.
  • Reducing toxic substance loads and remediating sediments will be beneficial not only to organisms that live on or in the sediments, but also to organisms that feed on them.
  • These actions will significantly improve and expand habitat for shellfish, finfish, and other estuarine life.
  • Risk to seafood consumers will be further reduced.
  • An improved toxic substance monitoring base will allow faster response to emerging problems and a greater ability to plan remediation activities.

Costs and Funding

    Successful implementation of the plan is contingent upon the states and the EPA receiving, at a minimum, level funding for existing programs associated with toxic substance controls, monitoring, and assessment. New funding of approximately $500,000 per year is needed to identify actions to remediate contaminated sediments in selected urban harbors at the rate of two harbors per year. Site-specific remediation cost estimates would be developed as harbor-specific analyses. New funding of $315,000 per year is needed to improve monitoring of toxic substances.

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