STATE OF THE GREAT LAKES 2005
WHAT ARE THE MAJOR PRESSURES IMPACTING THE ST. CLAIR - DETROIT
RIVER ECOSYSTEM?
Non-native invasive species, contaminants, and structural changes are threats to the St. Clair - Detroit River ecosystem.
Pressures
Non-native invasive species
Non-native invasive species have arrived and spread
throughout the St. Clair - Detroit River ecosystem.
Some recent invading species, such as tubenose goby,
have had very little impact on the community
ecology of the system, while other invading species,
including zebra mussels and purple loosestrife, have
significantly disrupted the ecology by causing
changes to food webs and excluding native species
from their preferred habitats. For example, in 1988,
the year zebra mussels were found in Lake St. Clair,
there were eighteen native mussel species inhabiting
the open lake. By 1994, only five of the original
eighteen native mussel species remained. White
perch colonized the St. Clair-
Detroit River ecosystem in 1977,
and caused dramatic changes to
the fish community by the late
1980s, including poor walleye
and yellow perch recruitment
and an increase in abundance of
muskellunge and smallmouth
bass.
Contaminants
Industrial, urban, rural, and
agricultural land use discharges
drain directly into the St. Clair
and Detroit Rivers and Lake St.
Clair, and often contain elevated
levels of sediment, nutrients,
bacteria, metals, and chemicals.
Historic contaminants such as
mercury, arsenic, dioxins, and
PCBs continue to cycle through
the sediments and the food web.
The presence of these
contaminants affects the health
and vitality of fish and wildlife populations and
results in consumption restrictions and beach
closures.
Structural changes
The shorelines of the St. Clair and Detroit Rivers are
highly urbanized and industrialized. Structural
changes include dredging and dyking to facilitate
shipping and to protect against flooding; and,
shoreline hardening, which involves building
structures to protect coastal lands from erosion.
These developments have altered the hydrology of
the St. Clair-Detroit River ecosystem, changing the
movement of sediments, and the location, extent, and
Major River Watersheds
D Anchor Buy
Clinton River
I Rouge River
D Huron River
River Raisin
Belle River
I I Sydenham River
D SL Clair River am)
Lake St. Clair Tributaries
15 Detroit River
and Lake Erie Tributaries
Major St. Clair River - Lake St. Clair - Detroit River watersheds. Source: Explore Our
Natural World: A Biodiversity Atlas of the Lake Huron to Lake Erie Corridor.
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ST. CLAIR - DETROIT RIVER PRESSURES
diversity of habitats. Significant amounts of the
watershed have also been altered, resulting in very
little natural habitat remaining in the St. Clair and
Detroit Rivers or their watersheds.
Current Actions
The Canadian and U.S. federal governments are
working with the province of Ontario and the state of
Michigan on two Remedial Action Plans (RAPs) and
the management of Lake St. Clair. The Detroit River
RAP includes control of combined sewer outflows,
point and nonpoint source pollution controls,
remediation of contaminated sediments, habitat
restoration, and pollution prevention, in addition to a
number of local and regional initiatives. The federal,
provincial, and state governments of Canada and the
United States are also working in partnership with
the St. Clair Binational Public Advisory Committee
on the St. Clair River RAP. Implemented in 1987, the
focus of the St. Clair River RAP is contaminated
sediment remediation on the Canadian side of the
river, elimination of combined sewer outflows and
sanitary sewer overflows on both sides of the river,
elimination of spills to the river from "Chemical
Valley" downstream of Sarnia, Ontario, and ensuring
proper notification when spills do occur.
Lake St. Clair management is currently overseen
through an agreement between Canadian and U.S.
federal governments, the state of Michigan, and the
province of Ontario. The recently released U.S .Army
Corps of Engineers St. Clair River/Lake St. Clair
Comprehensive Management Plan provides
implementation recommendations focusing on
environmental health, stressors relating to habitat
and biodiversity, human health (beach closures), land
use, fisheries, boating, commercial navigation, and
monitoring. A Lake St. Clair Canadian Watershed
draft Technical Report provides detailed information
about the state of the Canadian Lake St. Clair
watershed and identifies management issues.
Actions Needed
The implementation of activities to minimize
chemical inputs, manage sediment and nutrient
inputs, clean up contaminated sediments, reduce the
effects of exotic invasive species, prevent the
introduction of new exotic species, allow full human
body contact with waters of the connecting channels,
and monitor ecosystem changes, will improve and
confirm the quality of the St. Clair - Detroit River
ecosystem. The predicted effects of climate change
necessitates further research on how air temperature,
water levels, significant weather events, and ice cover
duration and thickness may have extensive and
dramatic effects for the St. Clair -Detroit River
ecosystem.
To Learn More
For further information related to the state of the St.
Clair - Detroit River Ecosystem, refer to the State of
the Great Lakes 2005 report which, along with other
Great Lakes references, can be accessed at
www.epa.gov/glnpo/solec. Information on the St.
Clair and the Detroit River RAPs can be accessed at
www.on.ec.gc.ca/water/raps/stclair/implement e.ht
ml and www.epa.gov/glnpo/aoc/detroit.htmlffstatus.
Walpole Island prairie in the St. Clair River delta. Photo:
G. M. Allen.
02/06
EPA 905-F-06-909
IISG-06-02
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