Prepared by: Michael A. Zarull, John H. Hartig, and Lisa Maynard
Sediment Priority Action Committee
Great Lakes Water Quality Board
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, U.S. EPA's 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 (Figure 1). While contaminated sediment is not designated as a specific impairment in Annex 2 of the 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
Figure 1. Great Lakes Basin Areas of Concern
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 (Table 1). 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.
This interim report of SedPAC reviews the following: what is known about contaminated sediment, sediment contamination and remediation in the Great Lakes, measurements of ecological benefits, and also presents advice to managers and researchers on future evaluation of ecological effectiveness of sediment remediation.
Table 1. Ecological performance use impairments potentially associated with contaminated sediment and the number of Areas of Concern (AOCs) where these impairments have been found
|NUMBER OF AOCs IMPAIRED (% OF 42 AOCs)|
|Restrictions on fish and wildlife consumption|
|Degradation of fish and wildlife populations|
|Fish tumors or other deformities|
|Bird or animal deformities or reproduction problems|
|Degradation of benthos|
|Loss of fish and wildlife habitat|
|Eutrophication or undesirable algae|
|Degradation of phytoplankton or zooplankton populations|