Prepared by: Michael A. Zarull, John H. Hartig, and Lisa Maynard
Sediment Priority Action Committee
Great Lakes Water Quality Board

August, 1999


Over the past 20 years, considerable progress has been made in the control and management of point and nonpoint sources of contaminants. Reduced loadings of contaminants have, in general, resulted in a 50-70% reduction of contaminant levels in fish between the early 1970s and the mid 1980s (Environment Canada and U.S. Environmental Protection Agency 1995; 1997). However, since the mid 1980s, ambient levels of contaminants appear to have generally either leveled off or their rate of decrease has slowed substantially. Health advisories on certain fishes remain in effect in all of the Great Lakes. It is believed that the major reason why contaminant levels in fish have generally leveled off and health advisories on human consumption of fish remain in effect is that there are continued inputs of contaminants from the atmosphere, land runoff, and contaminated sediment. As a result, the lakes are now a source of contaminants to the atmosphere, which in turn, deposits contaminants back into the lakes (Environment Canada and U.S. Environmental Protection Agency 1995; 1997).

The importance of the contaminated sediment issue continues to rise in both the United States and Canada. For example, the U.S. Environmental Protection Agency's (EPA) Region V has identified cleaning up contaminated sediment as one of its top six priorities in its Agenda for Action for fiscal year 1997 (U. S. Environmental Protection Agency 1997), and as one of its top five priorities in its Agenda for Action for fiscal years 1998 and 1999 (U. S. Environmental Protection Agency 1998a; 1999). The Agenda for Action states that:

Polluted sediments are the largest major source of contaminants to the Great Lakes food chain, and over 97% (8,325 km) of the shoreline is considered impaired. The Region V sediment inventory contains 346 contaminated sediment sites. Fish consumption advisories remain in place throughout the Great Lakes and many inland lakes. Contaminated sediments also cause restriction and delays in the dredging of navigable waterways, which in turn can negatively affect local and regional economies. Contaminated sediments must be cleaned up before they move downstream or into open waters, which makes them inaccessible and cleanup impossible.

Contaminated sediment has been identified as a source of ecological impacts throughout the Great Lakes Basin. All 42 Areas of Concern in the Great Lakes Basin have contaminated sediment based on the application of chemical guidelines. While contaminated sediment is not designated as a specific impairment in Annex 2 of the Great Lakes Water Quality Agreement (GLWQA), in-place pollutants potentially pose a challenge to restoring 11 of the 14 beneficial use impairments: restrictions on fish and wildlife consumption; degradation of fish and wildlife populations; fish tumors or other deformities; bird or animal deformities or reproductive problems; degradation of benthos; loss of fish and wildlife habitat; eutrophication or undesirable algae; degradation of phytoplankton or zooplankton populations; degradation of aesthetics; added costs to agriculture or industry; and restrictions on dredging activities.

The 14 beneficial uses identified in the GLWQA can be grouped into four aspects of ecosystem health or state: human health, societal value, economic value, and ecological performance. The first eight of the eleven beneficial use impairments identified above have to do with ecological performance. Therefore, restoration of their use and the realization of ecological benefit requires an understanding of the relationship between contaminated sediment and the specific use impairment. It is also imperative, prior to embarking upon sediment remediation, to have developed some quantifiable expectation of result (ecological benefit) and a program to follow the predicted recovery.

In most Areas of Concern, the documentation of the sediment problem has not been quantitatively coupled to the ecological beneficial use impairments. Therefore, stipulating how much needs to be cleaned up, why, and what improvements can be expected to the beneficial use impairment(s) over time has not been possible. A clear understanding of these relationships and some level of quantification is critical for the development of a complete sediment management strategy. This understanding should provide adequate justification for an active cleanup program, and also represents a principle consideration in the adoption of non-intervention alternative strategies. In developing this understanding, it is important not only to know the existing degree of ecological impairment associated with sediment contaminants, but also the circumstances under which those relationships and impacts might change (i.e., contaminants become more available or more detrimental).

Over the past thirteen years, over $580 million has been spent on 38 remediation projects in 19 Areas of Concern. Of these sediment remediation projects, only two currently have adequate data and information on ecological effectiveness (i.e., post-project monitoring of beneficial use restoration). In some cases there is planned monitoring of ecological effectiveness, but the data will not be available for a number of years. In the cases where sediment remediation was undertaken as a result of regulatory action, the projects were designed to remove a mass of contaminants to reduce environmental risk. These projects were very effective in meeting the regulatory requirements, and indeed are consistent with the step-wise and incremental approach to management of contaminated sediment called for by the Great Lakes Water Quality Board (WQB).

However, it is recognized that in many cases, much more effort should be placed on forecasting and assessing ecological recovery of an Area of Concern, as well as beneficial use restoration consistent with Annex 2 of the GLWQA. Therefore, SedPAC recommends:

One way of achieving this would be for the State/Provincial/Federal agency staff responsible for sediment remediation to incorporate into settlements and cooperative agreements some specific commitments and resources required for post-project monitoring of effectiveness of sediment remediation. Good examples of this include the Welland River project (Ontario), the settlement under the Natural Resource Damage Assessment for Saginaw River and Bay (Michigan), and the Thunder Bay cleanup project (Ontario).

Globally, the best documented ecological changes following sediment remediation are associated with actions relating to nutrient problems, generally in small lakes and ponds and in areas of low human population density, and usually the least costly remediations. Since affiliated research and monitoring have been so lacking, it has been difficult to evaluate the overall success of sediment remediation, in a general sense (i.e., to reasonably transfer lessons learned and recommendations on what things are still essential to know, and to achieve cost-effective and essential ecological remediation).

It is also recognized that ecological benefits of sediment remediation may not be seen because of the magnitude of the contaminated sediment problem in the area and in remaining downstream areas of contamination, which would mask or delay ecological recovery (e.g., Grand Calumet River/Indiana Harbor Ship Canal, Indiana). Areas of Concern where the probability of measuring ecological benefits of sediment remediation is high include: Manistique River, Michigan; Collingwood Harbour, Ontario; River Raisin, Michigan; Newburgh Lake Impoundment on the Rouge River, Michigan; and the unnamed tributary to the Ottawa River, Ohio. SedPAC recommends:

Although a basic understanding of aquatic ecosystem function and chemical fate is generally available, aquatic ecosystems appear to be sufficiently unique and our understanding sufficiently lacking. Therefore, an adaptive management approach is the prudent course to follow. This approach requires a much tighter coupling of research, monitoring, and management in every case to develop quantifiable, realistic goals and measures of success to achieve them.

Clearly, there are knowledge gaps in our understanding of the relationship between contaminated sediment and the 11 use impairments from the GLWQA that are potentially affected by contaminated sediment. Therefore, SedPAC recommends that: