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Great Lakes Ecological Protection and Restoration

Table of Contents


Chapter 1
Chapter 2
Chapter 3
Chapter 4
Chapter 5
Chapter 6
Chapter 7
Chapter 8

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Great Lakes Report to Congress 1994


February 1994
EPA 905-R-94-004

Chapter 6
Monitoring of the Ecosystem

This chapter discusses U.S. monitoring of the Great Lakes system, including three EPA initiatives on bioaccumulative toxic substances:

  1. Establishment of a binational Integrated Atmospheric Deposition Network (IADN) that will monitor airborne deposition of trace organics on a routine basis
  2. A multiagency study of the sources and fates of several bioaccumulative toxic substances in Green Bay
  3. Conversion and outfitting of a new ship to establish a capability to monitor trace organics in open-lake waters on a routine basis.

The chapter also discusses system-wide surveillance programs, including chemical and biological open- lake limnology, fish monitoring programs, the Great Lakes Atmospheric Deposition (GLAD) network, and the Environmental Monitoring and Assessment Program Great Lakes.


During recent years, there have been three primary elements of EPA's Great Lakes surveillance efforts: open-lake surveys of ambient water quality, monitoring of toxicant levels in fish tissues, and monitoring of atmospheric deposition. The Agency has conducted open-lake spring and summer surveys of ambient water quality in Lakes Michigan, Huron, and Erie since 1983, in Lake Ontario since 1986, and in Lake Superior since 1992. Prior to these routine surveys, each of the lakes was surveyed intensively. The current program includes nutrients (phosphorus, nitrogen, silica), conservative ions, alkalinity (alkali and alkaline earth metals), biological structure (phytoplankton and zooplankton), chlorophyll a, and physical parameters. Surveys measure conditions and trends in the open-waters of the Lakes. These waters best indicate long-term trends because they are less influenced by local discharges of pollutants than shallower, nearshore waters. The productivity measures obtained under the open-lake program enable EPA to assess the response of the Lakes to nutrient control measures and trends in plankton populations.

Since 1977, EPA, State, and other Federal agencies have monitored toxic organics in Great Lakes fish tissues. Fish are excellent indicators of water quality and ecosystem health because they tend to build up bioaccumulative toxic substances, whereas open-water concentrations of toxic organics are generally so low that it is difficult to monitor them directly on a routine basis.

With lake-to-lake variations in the number of collection sites and periodicity, States collect adult resident fish and spot-tail shiners from harbors and tributaries on a 5- to 10-year cycle and open-lake salmon as part of a game fish-monitoring program. The Food and Drug Administration analyzes the fish samples. The Fish and Wildlife Service also collects open-lake whole-fish samples of lake trout (walleye on Lake Erie) and smelt on a biennial basis for analysis by EPA. In addition, the Service has analyzed Lake Michigan bloater chubs for DDT and dieldrin since 1968, for PCBs since 1972, and for chlordane since 1982. States conduct additional fish-monitoring programs that are directed toward protecting human health by issuance of fish consumption health advisories.

The third primary element of EPA's surveillance activities, also a joint Federal/State endeavor, is monitoring of atmospheric deposition. The United States operates a 20-station GLAD network. GLAD presently addresses nutrients and metals, including lead, cadmium, nitrate/nitrite, and phosphorus, among about 35 parameters.

In addition, States and the U.S. Geological Survey monitor Great Lakes tributaries for pollutants on an ongoing basis, since tributaries are major conveyors of pollutants from both nonpoint and point sources.

Since 1991, in cooperation with other Agencies, EPA has begun to design and implement a monitoring program whose goal is to estimate conditions in the Great Lakes with known confidence.

The Environmental Monitoring and Assessment Program (EMAP) Great Lakes is an interagency interdisciplinary program whose goals are to monitor and assess the condition of the Great Lakes and to contribute to decisions on environmental protection and management. EMAP Great Lakes has four objectives:

  1. Estimate the current status, trends and changes in selected indicators of the condition of the Great Lakes on a regional basis with known confidence;
  2. Estimate the geographic coverage and extent of the harbors, bays and wetlands;
  3. Seek associations between selected indicators of natural and anthropogenic stresses a indicators of condition of ecological resources;
  4. Provide annual statistical summaries and periodic assessment of the Great Lakes.

For the Great Lakes, the individual lakes have been established as the regional scale of resolution and each lake will be separated into resource classes (offshore water, nearshore, bays/harbors, and wetlands) with sampling frames and indicators that are appropriate to characterize each class. Biotic integrity and trophic condition have been identified as important environmental values. These values will influence the selection of indicators and assessment questions for the offshore, nearshore and bays/harbors resource class. To assess overall biotic integrity, EPA has focused on three major components: benthic macroinvertebrates, primary producers, and fish.

Integrated Atmospheric Deposition Network Back to Top

Since the late 1970s, the Great Lakes scientific community has been aware of the potential significance of the atmosphere as a pollution pathway. Studies of Isle Royale, a relatively isolated island in Lake Superior, revealed levels of PCBs, toxaphene, and other bioaccumulative toxic substances in its lakes. Researchers theorized that such pollutants could only have resulted from atmospheric deposition.

Since the Isle Royale findings, EPA has promoted ways of assessing the absolute and relative magnitude of atmospheric loadings of toxic substances. The Agency supported conferences in 1980, 1986, and 1987 to assess the state of knowledge of the airborne deposition problem and developed a strategy in 1987 to monitor these substances. In recognition of the potential importance of air deposition to the Great Lakes, the United States and Canada agreed in 1987 to establish an Integrated Atmospheric Deposition Network (IADN) to monitor both wet and dry atmospheric loadings of toxic substances to the Great Lakes.

It should be noted that the concentrations of toxic organics in precipitation are very minute and, therefore, difficult to collect and analyze. Scientists are developing methods to do this routinely, and it is likely that the feasibility of monitoring atmospheric deposition will differ from parameter to parameter. EPA implemented its first master station and two satellite stations for monitoring airborne PCBs and dieldrin in fall 1988. These are located around Green Bay.

During FYs 1989 and 1990, the United States and Canada coordinated various management, parameter, siting, and methods issues pertaining to establishment of a network to monitor atmospheric deposition of bioaccumulative toxic substances. During 1991, the two nations completed the installation of one IADN master station on each of the Great Lakes . The United State has established master stations on Lakes Superior, Erie, and Michigan, while Canada has established them on Lakes Huron and on Ontario. Data will be shared by each nation, and the United States will be able to place equipment at the Lake Ontario site.

Green Bay Study Back to Top

This special study, begun in 1987, has helped EPA develop an understanding of the sources, pathways, and fates of PCBs within a large waterbody. The Wisconsin Department of Natural Resources and EPA's Great Lakes National Program Office were the major sponsors of the study, with aspects supported by EPA's Environmental Research Laboratory-Duluth, Minnesota, and its Large Lakes Research Station at Grosse Ile, Michigan; the Great Lakes Environmental Research Laboratory and Wisconsin Sea Grant of the National Oceanic and Atmospheric Administration; the U.S. Geological Survey; the Michigan Department of Natural Resources; the U.S. Coast Guard; the Illinois State Water Survey; and a number of universities.

Numerous field activities were undertaken during FYs 1989 and l990. EPA's Research Vessel, the Roger Simons, conducted a field sampling shakedown cruise on Green Bay in October 1988 and conducted five sampling cruises in May, June, July, September, and October 1989. A winter survey was conducted from a U.S. Coast Guard helicopter in February 1989. Another winter survey and a spring survey were conducted in FY 1990. In cooperation with the Wisconsin Department of Natural Resources and the U.S. Geological Survey, tributary monitoring was performed on all important tributaries to Green Bay. Wisconsin also collected fish samples. A master and two routine monitoring stations collected air deposition samples. Other studies addressed water/land/air vapor flux of contaminants, groundwater loadings, and sediment contamination.

The study has refined laboratory methods for handling a large number of samples that must be analyzed for trace organics. Detection of these trace contaminants in the water column requires sampling large volumes of water. Previously, such analyses were, in essence, small-scale research activities. However, the Green Bay Study has developed methods that can be employed on a more routine basis.

In FY 1991, the study team completed analysis of samples, compiled data, and calibrated existing models. Study findings were developed in FY 1992.

New Research Vessel Back to Top

Early in 1990, EPA concluded negotiations with the U.S. Department of Transportation Maritime Administration for purchase of a vessel that was subsequently converted into a replacement research vessel for open-lake water quality monitoring. This vessel was needed because the previous ship was more than 50 years old. The new vessel has more capabilities than the old ship and will expand the capability for routine monitoring of bioaccumulative toxic substances in open-lake waters. The new vessel, christened the Research Vessel Lake Guardian, underwent shipyard conversion during the second half of 1990. It began operations during FY 1991.

System-wide Surveillance Back to Top

During 1992, the Agency accomplished all open-lake water quality sampling that was planned for Lakes Erie, Huron, Michigan, and Ontario. During he summer survey, EPA sampled for 33 parameters at 20 sites in Lake Erie, 20 sites in Lake Huron, 11 sites in Lake Michigan, and 8 sites in Lake Ontario. spring and summer surveys were also completed in 1990 and 1991.

Through an agreement with the Fish and Wildlife Service, the Agency supports an annual monitoring program for dissolved oxygen in Lake Erie. Dissolved oxygen is measured from June through September at 10 stations in the central basin of Lake Erie. Oxygen depletion rates in Lake Erie's central basin were lower in 1988 and 1989 than at any time in the last 20 years. In 1989, the bottom waters did not become anoxic, although severely reduced dissolved oxygen levels were observed in mid-September, which is an encouraging sign that phosphorus load reductions may be achieving their desired effect. In several previous years, anoxic conditions developed about mid-August.

EPA, States, and the Fish and Wildlife Service continued fish surveillance programs during FY 1992; this activity will continue during FY 1993. Figures 6-1 and 6-2 show some results of this monitoring program. Figure 6-1 shows that PCB levels in coho salmon have been highest in Lake Ontario during the 1980s. Figure 6-2 shows PCB contamination in another predator species, lake trout, is higher than in coho. States and EPA continued their joint support of a 20-station atmospheric deposition network during 1992; this activity will continue during FY 1993. The sampling stations monitor nutrients (nitrate/nitrite and phosphorus), metals (including lead, cadmium, and mercury), and acidity in precipitation among about 35 parameters. States and universities operate the sampling stations and provide samples to EPA on a weekly basis, if sufficient precipitation occurs.

EPA, Environment Canada's National Water Research Institute (NWRI) and NOAA-GLERL conducted EMAP Great Lakes pilot activities on Lakes Michigan and Superior in FY 1992. Spring surveys were completed on both lakes, while two additional surveys, one summer and one fall, were completed on Lake Michigan. Offshore trophic status from EMAP grid sites was assessed. Measurements of spring trophic status were sampled at 12 EMAP sites in Lake Michigan and at 19 EMAP stations in Lake Superior. During the summer cruise in Lake Michigan, sediments were collected to examine variability in offshore benthic macroinvertebrate communities and to assess the adequacy of the base grid sampling intensity. The fall cruise in Lake Michigan was part of a cooperative nearshore study with NWRI and NOAA-GLERL to assess the adequacy of sampling intensity and sampling method (Ponar vs. box core). Benthic macroinvertebrates in nearshore areas will be used to determine nominal conditions in Lake Michigan.

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