FINAL REPORT - International Joint Commission

FINAL REPORT
The current estimate of the area of coastal wetlands within Lake Ontario and the upper St. Lawrence River
is approximately 26,000 hectares (64,250 acres), made up of four basic types: submerged aquatic vegetation,
emergent marsh, meadow marsh, and upland vegetation (trees/shrubs) (Wilcox, et al. 2005). Over 80%
of the wetland area occurs in the eastern half of the Lake Ontario basin and Thousand Islands region.
Results from study site analysis indicate that there has been a 50% reduction in meadow marsh and in
emergent-floating vegetation since regulation was implemented in the late 1950s. During that same time
period, there has been a 29% increase in cattail-dominated emergent marsh area (about 1,700 hectares
or 4,200 acres) (Wilcox and Ingram, 2005).
With over 12,000 hectares (30,000 acres) of swamps and marshes, Lac Saint-Pierre accounts for 80% of
lower St. Lawrence River wetlands. Lac Saint-Pierre supports a large population of nesting blue herons
(more than 1,300 nests), a major staging area for migratory wildfowl (more than 800,000 ducks and geese
annually) and 167 species of nesting birds. Permanently submerged areas, wetlands and the spring
floodplain are home to 13 amphibian and 79 fish species, many of which are exploited by sports and
commercial fisheries alike (Centre Saint Laurent, 1996). The ecological value of Lac Saint-Pierre has been
recognized by its status as a Ramsar wetland and a UNESCO Biosphere Reserve, and its inclusion as a
protected site under the Eastern Habitat Joint Venture.
In addition to impacts caused by regulation, changes in climate, water temperature, and water supply can
affect the environmental response of habitats and the species they support. Issues such as invasive
species, changes in fisheries management, pollution and population changes, or changes in the use of the
resource can also impact the environment. Regardless of the regulation plan, the environment will
continue to be vulnerable to various stressors such as invasive species, pollution, and land use changes.
However, how lake levels are managed can have an impact on the ecological integrity of the system and its
resilience to these other stressors.
New Information and Science
This Study was a catalyst for new research into the physical inventory of the basin and the relationships
between water levels and flows and economic and environmental impacts. In this Study, the quantified
impacts were called “performance indicators.” A performance indicator measures impact on a use. For
example, the cost of flood damages avoided affects the use of the coast for human habitation. Each technical
work group conducted research to quantify the relationship between impacts and different water levels and
flows, ultimately developing mathematical relationships, defining impact in quantitative terms as a function
of water levels and flows, that were used to evaluate the impacts of alternative plans. The quantitative
evaluation of impacts was carried out in terms of economic and environmental measures, while social
considerations, which may also be important, were captured qualitatively in the contextual narratives.
The key performance indicators chosen by each of the technical work groups are listed in Table 1. Annex 2
of this report provides more details on these indicators, and still greater detail can be found in supporting
documentation available through the Study website (www.losl.org), including a summary fact sheet on
each of the performance indicators listed. It is important to note that the Environmental Technical Work
Group began with 400 performance indicators, but reduced this to 32 key performance indicators based on
the sensitivity of the indicator to changes in water levels and flows, the significance and representativeness
of the indicator, and the certainty in the research. Environmental scientists within and outside the Study
discussed the plan evaluations online and in workshops, trying to rank plans based on the overall benefit
to the environment. These ranking efforts showed that scientists attached particular significance to an
even smaller subset of these 32 indicators, either because of special importance (species at risk) or the
representativeness of one species for larger ecosystem effects (muskrat house density in the upper river).
The indicators in the smaller subset are marked by an asterisk in Table 1.
16 Options for Managing Lake Ontario and St. Lawrence River Water Levels and Flows