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Lake by lake: Huron
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Lake Huron is the third largest of the lakes by volume, with 850 cubic miles of water. Lake Huron is hydrologically inseparable from Lake Michigan, joined by the wide Straits of Mackinac. The Huron lakeshore extends 3,827 miles, and is characterized by shallow, sandy beaches and the rocky shores of Georgian Bay. The lake measures 206 miles across and 183 miles north to south, with an average depth of 195 feet (approximately 750 feet, maximum). Lake Huron's drainage area, which covers parts of Michigan and Ontario, is relatively large compared to the other Great Lakes. It's more than twice the size of Huron's approximately 23,000 square miles of surface water. The Saginaw River basin is intensively farmed and contains the Flint and Saginaw-Bay City metropolitan areas.

Drinking water
Microbial contamination | Chemical contamination | Critical contaminants

Microbial contamination
Pathogens refer to bacterial organisms (microbes) typically found in the intestinal tracts of mamals, capable of producing disease. Sources of nutrients include municipal wastewater treatment plants, septic systems, and agricultural runoff. Areas of Lake Huron where pathogens are of concern are Saginaw Bay, Severn Sound, and the southeastern shore of the Lake Huron Basin. Effects of pathogens in these regions have included localized beach closings due to e. coli contamination.

In an effort to learn more about microbial contamination and to eliminate sources of pollution, continued monitoring, determination of the source of pathogens, and prevention activities are planned or active around Lake Huron as well as along the tributaries listed above.

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Chemical contamination
Contaminants to Lake Huron originate from a number of sources, including industrial and municipal discharges, spills, landfills, storm sewers, and agricultural runoff. Contaminants enter Lake Huron through a variety of pathways including direct discharges, atmospheric deposition, and tributary discharge. In comparison to Lakes Michigan, Erie and Ontario, contaminant concentrations are relatively low in Lake Huron. Nevertheless, public health advisories exist regarding consumption of trout from the open lake and all Areas of Concern (AOCs).

The large surface area of Lake Huron, like the other Great Lakes, has made it particularly vulnerable to atmospheric deposition of contaminants. Lake Huron has a large surface area and relatively few local contaminant point sources. Loadings to Lake Huron from water sources are lowest of all the Great Lakes but air sources are highest.

From the late 1970ís to the early 1990ís, persistent, bioaccumulative substances (such as PCBs, DDT, dieldrin, dioxins, and furans) concentrations declined significantly in Lake Huron lake trout. However, while concentrations of DDT have continued to decline, PCB concentrations have not declined significantly since the mid-1980s. DDE trends in Lake Huron herring gull eggs show a marked decrease in concentration since the mid 1970s. As with other trends, concentrations decreased significantly in the late 1970s but have remained relatively stable since. Continuing sources of contaminants are primarily from sediments contaminated by historic discharges, airborne deposition industrial and municipal discharges and land runoff.

Originally, there were six Great Lakes areas of significant environmental contamination or Areas of Concern (AOCs) on Lake Huron. One of these, Collingwood Harbour, Ontario, was the first and remains the only AOC to be delisted. The St. Marys River is designated as an AOC because of contaminants from sediment, municipal discharges and nonpoint source pollution sources. Control of industrial point sources is progressing and pollution loads are being reduced. The St. Clair River is designated as an AOC because of the pollution problems on the eastern side of the river.

Two other Canadian Areas of Concern, Spanish River and Severn Sound are responding well to remedial actions and showing recovery. The only Area of Concern solely in Michigan, Saginaw River/Saginaw Bay, is designated as an Area of Concern primarily because of contaminated sediments and nonpoint pollution sources.

Historically, phosphorus has been a significant problem in the Great Lakes. To a great extent this has not been the case in Lake Huron, with the exception of Saginaw Bay and the southern Ontario shore. The United States/Canada Great Lakes Water Quality Agreement (GLWQA) identified target loads for all lakes to prevent phosphorus-related problems (over enrichment), and Lake Huron has generally maintained loadings below target loads. With the exception of 1982 and 1985, loadings have been below the target since 1981.

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Recreational water
Beaches | Critical contaminants

The Lake Huron nearshore terrestrial ecosystems sustain an amazing diversity of wildlife that enriches the Lake Huron Basin. The physical structure and living communities of this area are as much a function of the lake's ecosystem as the fish in its depths. The action of waves and wind shape the beaches, dunes, and shore bluffs. These land forms and the local climate effects determine the biological communities. These communities, in turn, sustain the amazing diversity of wildlife.

The shoreline of Lake Huron is the longest of the Great Lakes, its length extended by the shores of its numerous islands and bays. Rocky shores associated with the Precambrian shield cover the northern and eastern shores, limestone dominates the shores of Manitoulin Island and the northern shore of the Bruce Peninsula, and glacial deposits of sand, gravel, and till predominate in the western, southern, and south-eastern portions of the shore. Shoreline and inshore habitats are correspondingly diverse.

Many nearshore areas of Lake Huron have been altered due to human influences. The once natural shorelines offered fish and wildlife significant habitat for all of their life stages. Due to development in coastal areas, many areas now have shoreline protection structures. In many cases, the narrow band of transitional vegetation is now gone. The cumulative impact of these structures throughout the basin is significant and increasing.

In general terms, the state of health for specific nearshore terrestrial habitats in the Lake Huron ecoregions ranges from stable (northern portions of the basin), to moderately degrading (central portions of the basin) to severely degrading (southern portions of the basin). General threats to the nearshore areas include agriculture, shoreline development, and sedimentation.

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Fish consumption
Critical contaminants | Reducing exposure
Specific fish advisories: Michigan | Ontario

Michigan Fish Consumption Advisories
Michigan Fish Advisory
A Family's Guide to Eating Fish from the Lake Erie Basin

Eating Ontario Sport Fish
A Family's Guide to Eating Fish from the Lake Erie Basin
Mercury in Fish: A Special Advisory (PDF)
Mercury and Fish Consumption
Information on mercury levels in fish

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