Synthesis: Impact of Water Level Management on Species-at-Risk In
Lake Ontario and the Upper St. Lawrence River
Jana Lantry, Albert Schiavone and John Farrell
Introduction
The International Joint Commission has undertaken a five-year study to develop
and evaluate alternative water level regulation plans for Lake Ontario and the upper St.
Lawrence River. The objective of our study was to evaluate the potential impacts of each
proposed regulation plan based on positive or negative changes in needed or preferred
habitat of the species-at-risk associated with nearshore and wetland areas. More
specifically, we integrate occurrence, life history and habitat information for threatened
and endangered species with models developed to evaluate the impact of proposed water
level regulation plans on habitat availability. The vegetative and faunal models are
incorporated into the Integrated Ecological Response Model (IERM), which will provide
us with predictions of habitat availability for each water level scenario and wetland
habitat or vegetative structural type (Table 1). We will use Rank-Sum-Analysis to
evaluate the impact of each proposed regulation plan on habitat availability for each
species as determined from model predictions. Ultimately, we will determine which
proposed Lake Ontario-St. Lawrence River water level scenario is most suited to the
needs and interests of species-at-risk.
Importance of our study in relation to the overall study
Protecting habitat for species-at-risk is essential to conserve and protect
ecosystems and biodiversity. The U.S. and Canadian federal governments, province of
Ontario, and state of New York have many laws written to protect wildlife. For speciesat-risk, these laws are written, in part, to prevent or minimize damage to critical habitat.
Loss of habitat is often the cause for declining populations of species-at-risk; therefore,
critical habitat must be protected. Our study will help to evaluate the impact of proposed
water level regulation scenarios on habitat availability. For species-at-risk, we do not
want any negative change in habitat availability as compared to the baseline scenario
(1958DD) and the no regulation scenario. Assessment of the significance of relative
changes in habitat availability will then allow us to develop new criteria.
We base our evaluation approach on the following assumptions:
 Abundance and distribution of the species-at-risk are currently limited by available
habitat
 Literature provides accurate information on life history and habitat needs and preferences
 Habitat and/or vegetative structural type designations are comparable to the designation
as determined from the Wilcox’s vegetative model output
 Wilcox’s vegetative model allows us to predict quantitative changes in species preferred
habitat or vegetation for each water level scenario
 The faunal models developed for the Lake Ontario-St. Lawrence River Water Level
Study are valid

Habitat distribution and availability are not affected by other system changes (i.e.
Dreissena mediated changes in water clarity, lower level productivity, climate change
impacts on water temperature, non-indigenous species introductions, other human
mediated changes, etc.).
Judgments as to uncertainty
There is uncertainty associated with each of our assumptions, and includes:
 The suspected distribution of each species is only as good as available
occurrence information.
 We assume that species are currently limited by available habitat.
Conversely, even if the models predict a certain amount of available
habitat for a given species, that species may only be able to occupy a
portion of that habitat for a number of reasons (i.e. proximity to humans,
wetland complexity, pollution, faunal wetland species composition and
diversity, etc.).
 Information on life history and habitat needs and preferences as
determined for literature review may not apply to the entire study area (i.e.
population dynamics may be different for a populations found in Lake
Ontario, in the upper St. Lawrence River, or elsewhere).
 There may be uncertainty with how the forcing functions (i.e. water level)
interact with habitat.
 There are uncertainties associated with each of the models (vegetative and
faunal) that are being used to predict habitat changes and should be
addressed by the individual modelers.
 There are influences on the system, other than water level, that will likely
influence study results (i.e. Dreissena mediated changes in water clarity,
lower level productivity, climate change impacts on water temperature,
non-indigenous species introductions, other human mediated changes,
etc.).
Key Results (to date)
We identified and determined occurrences of 51 officially protected species
associated with nearshore and wetland areas and found within areas potentially impacted
by water level regulation (Table 2). For each of these species, we closely examined
distribution, status, habitat needs and preferences, life history information, and expected
causes for decline. Many of these species are found in areas where the impacts of water
level regulation are unclear and expected to be at the most minimal (e.g. tributaries, fens
and bogs of Lake Ontario and the upper St. Lawrence River) or where water levels are
not a primary influence on habitat availability, population dynamics, or a cause for
decline.
For the purposes of this study, we focus on 13 species for which water level
fluctuation is a primary cause of changes in habitat availability, population dynamics, or
cause for decline (Table 3). We summarized distribution and status, important habitat
needs and preferences, and life history information needed by the faunal modelers for
each species. These summaries were developed from literature review, selected field
sampling, NYNHP and ONHIC information, and expected output from Wilcox’s
vegetative model. Detailed species-specific information was provided to the faunal
modelers (Table 1). Each faunal model is built into the IERM, which will provide us
with predictions of habitat availability for each of the 13 species-at-risk.
We completed selected field sampling to confirm the presence of a fish species-atrisk and its associated wetland habitat type. We seined sites in 11 waterbodies along the
Lake Ontario and the St. Lawrence River shoreline (Table 4). 10 out of the 14 fish
species-at-risk had previously been captured in the waterbodies sampled. We
successfully captured six of these fish species and were able to confirm available
published habitat descriptions for all of them (redfin shiner, pugnose shiner, bridle shiner,
rosyface shiner, eastern sand darter, and channel darter). Habitat information collected
during our sampling, supplements existing published information for all of the species
that we captured.
Results expected from the IERM after March
For each of the species that we are focusing on, we will obtain predictions of
habitat availability (i.e. fish weighted suitable area, bird habitat suitability, % coverage by
habitat or vegetative structural type for reptiles and plants, and area of dune erosion and
deposition) as output from the IERM (fish, birds, reptiles and 1 wetland plant species)
and the dune model developed by Pete Zuzek (CTWG; 3 dune plant species). We will
evaluate the potential impacts of each proposed regulation plan based on positive or
negative changes in species-specific needed or preferred habitat.