FINAL REPORT - International Joint Commission

Hydrology, supplies
Historical and
stochastic
series
ANNEX 2
Regulation plan
Water levels (Lake Ontario and St. Lawrence)
and flows (St. Lawrence)
Dam releases
Wetlands, suitable habitat
Fish
Floral and faunal species
Mammals
(muskrats)
Env PIs
Species at risk (SAR)
Birds
Herptiles
Figure A-1: Information flow in developing Environmental Performance Indicator responses
The Study Board and the Environmental Technical Work Group recognized the need for an integrating
framework to permit all environmental performance indicators to be driven by the same set of forcing
functions (water levels and flows, and their impact on habitat within the study domain), and to allow for
simultaneous evaluation of all environmental performance indicators in the interest of ensuring that
conflicts might be identified and understood. The Environmental Technical Work Group chose to use an
integrated modeling framework, called the Integrated Ecological Response Model (IERM), to formulate and
integrate its quantitative understanding of how the water level and flow-sensitive ecosystem components
represented by the performance indicators would respond to alternative plans.
The development and application of the IERM was led by Limno-Tech Inc., in close cooperation with fellow
modelers for the lower St. Lawrence River from Environment Canada-Quebec Region, and the entire
Environmental Technical Work Group. Regular interaction throughout the study with other technical work
groups, the Plan Formulation and Evaluation Group, and the Study Board contributed to the final product.
The IERM was consistent with the Shared Vision Planning process developed for the Study and became
the environmental wing of the Shared Vision Model (SVM).
In accordance with direction from the Study Board, one of the key assumptions used in formulating the
IERM was that the model was not to consider the response of various performance indicators to forcing
functions other than water levels and flows and temperature. Other recognized important stressors on the
Lake Ontario–St. Lawrence River ecosystem—such as nutrient and sediment supplies from the watershed,
toxic chemical exposure, land use changes, nuisance exotic species invasions, and, in the case of some
species, stocking and harvesting practices—were assumed to be constant among the various planscenario
conditions tested.
Options for Managing Lake Ontario and St. Lawrence River Water Levels and Flows
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