ECOLOGICAL BENEFITS OF
CONTAMINATED SEDIMENT
REMEDIATION IN THE
GREAT LAKES BASIN

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

August, 1999


VII. CONCLUSIONS AND RECOMMENDATIONS

All 42 Areas of Concern in the Great Lakes Basin have contaminated sediment based on the application of chemical guidelines. In addition, there is a consensus among government, industry, non-governmental organizations, and RAP groups that contaminated sediment is a major cause of environmental problems, as well as a key factor in restoring 11 of the 14 beneficial use impairments identified in the GLWQA.

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 in order 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 WQB (SedPAC 1997). 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 generally the least costly remediations. Since affiliated research and monitoring has 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., see Grand Calumet River/Indiana Harbor Ship Canal and Milwaukee Estuary in Table 2). 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 relationships between contaminated sediment and the 11 use impairments from the GLWQA that are potentially affected by contaminated sediment. Therefore, SedPAC recommends that: