Water Availability: An Overview of Issues and Futur e

Challenges for the St. Lawrence River (Quebec Studies, 2006-02-13)

Jean-François Bibeault, Ph.D. and Christiane Hudon, Ph.D. Environment Canada

105 McGill, Montreal, Que.

Introduction

For some years now, water availability in the St. Lawrence River has been an inherent

part of the larger issues threatening the integrity of its aquatic ecosystems. The St.

Lawrence system (including the Great Lakes) is among the three largest in North

America, alongside the Mackenzie and Mississippi rivers, in terms of basin size and flow

rate..Located downstream of the international section (Kingston to Cornwall, Ontario),

the Quebec portion of the St. Lawrence comprises four major bio-geographic units: the

fluvial section, which is primarily influenced by Great Lakes inflows, the freshwater tidal

portion of the fluvial estuary, the saltwater transition located in the upper estuary and the

lower estuary, which widens up to become the Gulf of St. Lawrence (SLC 1996).

Despite its large size, the St. Lawrence is subject to a range of anthropogenic pressures

including variations in water availability, which reveal its vulnerability to hydrological and

climatic factors.

To fully appreciate the issues at stake in the fluvial section, we must first examine the

context in which the Great Lakes–St. Lawrence was transformed. Specific aspects

relating to fluvial integrity will then be described using the case of Lake Saint-Pierre, a

designated Biosphere Reserve (UNESCO) and Ramsar site, as an example. Lastly, we

will examine the current pressures on the ecosystem and future risks to water

availability.

1. Major Transformation of the Great Lakes–St. Lawr ence System

Like many of Canada’s freshwater basins, the Great Lakes and St. Lawrence River are

subject to a wide range of pressures (NWRI and CMS 2004), which started to amplify

mainly at the end of the Second World War and steered land-use development and

water use toward the present-day conditions. The main trends illustrating these

modifications can be summarized as follows. First, the production capacity of the basin

grew considerably throughout the 20th century while the population’s consumption

patterns changed noticeably. The result: a plethora of synthetic chemical, non

degradable substances of now confirmed toxicity, increasingly dense industrialization

and urbanization of shorelines, and the growth of commercial navigation (seaway and

shipping channel) to facilitate imports and exports of raw materials and finished goods.

Second, the energy demand also rose during this same period and the construction of

dams at Beauharnois and Cornwall/Massena (Moses–Saunders Dam) increased the

capacity to regulate discharges and flows. And third, water needs for purposes other

than industrial production or domestic consumption then diversified with the upsurge of

recreational activities in the 1960s and 1970s. Water required for human health and

quality of life also took on new importance. These trends interacted and over time, and

the combined effect of these massive socio-economic changes translated into concerns

about the quality of water and the environment, specifically the emergence of ecological,

aesthetic (Maître and David 2000) and cultural values and questions of identity linked to

the water.

In Canada, including Quebec, these concerns gave rise to new public policies and

initiatives focusing on the biophysical environment.

2. Water Management: From Resource development to s ustainability

Water availability is governed by the combination of precipitation, inputs from upstream

basins, groundwater (and recharge), runoff, evaporation, diversions to or from a basin,

and the regulation of water levels and flows (IJC 2000). Other variables affecting water

availability include modification of the profile or depth of rivers and lakes, surface sealing

(e.g. pavement in urban settings), transformation of plant cover (e.g. agriculture and

forestry practices), control of ice jams, climate change, and water removals for a wide

range of purposes1. All these factors modify the quantity, the timing and overall

availability of water and exert an impact on the sustainability of ecosystems, habitats

and species.

On an institutional basis, water quantity was primarily looked at from a resource point of

view. Measures were taken by the Canadian and Quebec governments to reduce the

pressure on the water resource and on the St. Lawrence ecosystem.

The Canada Water Act (L.R. 1985, ch. C-11) of 19702 marked a turning point for federal-

provincial agreements in matters related to the planning and management of fresh

water, including targeted research, conservation projects and the efficient use and

enhancement of water (s. 5)3. In 1978, this framework legislation made possible the

adoption in Quebec of a federal-provincial flood control program, largely instigated by

flooding of the St. Lawrence in 1974 and especially 1976. This legislation however

responded mainly to economic rather than environmental considerations; the main

objective being to limit governmental monetary compensation for flooded private

properties located in the floodplain.

The Quebec government then specifically turned its attention to the St. Lawrence River.

With the Archipel project (1979-1984) and the 1985 Archiparc project, the focus was on

the Montreal archipelago. Although the latter project never saw the light of day, it did

lead to the gradual re-appropriation of the shoreline for municipal parks in the Montreal

area.

Interest in the St. Lawrence was subsequently marked by the implementation of

successive federal-provincial action plans between 1988 and 2003, following the

Federal water policy developed in 1987 and the parallel development and tabling of a

provincial policy on marine and river transport (1998). There followed the first Quebec-

wide water policy (Politique nationale de l’eau) in 2002, which focused on integrated

management of the St. Lawrence River and on a multilateral strategy (governments,

private sector and NGOs) for sustainable navigation on the St. Lawrence (see D’Arcy et

al. 2004). From 1988 to 2003, many hundreds of millions of dollars were invested for St.

Lawrence Action plans implementation.

Following an international movement (e.g. UICN conservation strategy in 1980, Eco-

development concept by I. Sachs), conservation became part of the political and

administrative agendas. On the conservation front, various programs and policies were

launched starting in the late 1980s. In addition to the Species at Risk Act (adopted in

2002, in force since 2004), which emphasizes habitat protection, there is growing

interest in environmental conservation, especially of wetlands. The federal wetland

conservation policy adopted in 1991 advances a series of principles, including the

principle of no-net loss of wetland function and that of safeguarding and recovering

wetland areas. This policy was the first to consider water availability in the context of

environmental sustainability.

Perspectives, too, have evolved between 1970 to the present day. The

compartmentalized management approach wherein resources and ecosystems were

treated independently of each other has largely given way to a heightened political

sensitivity to the dynamic nature of the environment. Public pressure from environmental

groups and by managers that played advocacy roles internal to governmental

organizations, combined to foster a new water management approach.

At the same time, our knowledge of the ecology of the St. Lawrence has also improved,

especially since the mid-1990s. The recent concerns of research scientists about water

levels and regulation of the St. Lawrence have led to advances which, on some level,

have led to a more concrete diagnosis of the state of the fluvial environment.

This recent shift in perspective is exemplified by the concomitant change in the

institutional approach regarding management of levels and flows in the Lake Ontario

and the St. Lawrence River.

3. Regulation of the St. Lawrence River: A Historic ally Fluctuating Issue

The hydrological regime of the St. Lawrence River is quite distinctive, being at once

subject to natural factors and to upstream flow regulation (figure 1). Water availability

issues were first considered in the early 20th century, through the management of

international waters, bringing on the Boundary Waters Treaty (1909) between Canada

and the United States and the creation of the International Joint Commission in 1911

(Institute of the Environment and Clinton Edmonds and Ass. Ltd. 2002). In this era,

explicit mention was made of the interests and priority of uses of the Great Lakes–St.

Lawrence Basin (sec. VIII of the Treaty). Precedence was then given to use of the water

for domestic and sanitary purposes, followed by navigation4, including the operation of

shipping channels, and then to energy production and irrigation5.

Figure 1. Profile of Lake Ontario and the St. Lawr ence River (Montreal)

Almost 50 years later, the level and flow management system for the St. Lawrence was

reviewed (Figure 1), and a tentative water-regulation plan saw the light of day (Plan

1958-D). Developed simultaneously with the construction of the international seaway

and of the Moses-Saunders Dam, Plan 1958-D used criteria and rules of operation to

balance the interests of commercial navigation, hydro-electric energy production and

flood control. The International St. Lawrence River Board of Control (ISLRBC) was

created at the same time (1959) to oversee application of these rules and criteria. Plan

1958-D was adopted with minor adjustments and implemented in 1963.

Shortcomings in application of Plan 1958-D — especially the lack of consideration for

riparian owners — became obvious almost immediately, in part owing to the unexpected

occurrence of water supplies below (early 1960s, late 1990s) and above (mid-1970s)

those of the historical sequence from which Plan 1958D was developed. As a

consequence, the ISLRBC was requested by user groups to deviate on an ad hoc basis

from the prescribed flow releases nearly half the time (Carpentier 2003), mostly to

maintain water levels for commercial navigation or to prevent flooding and shoreline

erosion.

Dissatisfaction with the plan prompted the IJC to lead four attempts to revise6 it. The

most recent effort fell to the International Lake Ontario-St. Lawrence River Study Board,

mandated by the IJC to undertake a five-year study (2000–2005) of regulation criteria for

Lake Ontario and the St. Lawrence River (IJC 1999)7, leading to the presentation of

alternative regulation plans to the IJC Commissioners (International Lake Ontario-St.

Lawrence River Study Board 2005).

The alternative plans derived from the 2000-2005 study were particularly innovative

since they included anticipated impacts on the environment and on recreational boating

activities, in addition to those of users already included in the Boundary Waters Treaty

(1909). Each user group, including the environment, was represented by a technical

working group (TWG) involving natural sciences specialists from different organizations

in Canada and United States and whose mandate was to develop performance

indicators allowing a determination of the impacts of the proposed alternative plans, and

eventually help to reduce anticipated negative impacts. In the case of the environmental

aspects, the TWG was charged with the identification of relevant indicators for

assessing the ecological sustainability of different regulation plans. As with other similar

efforts (see Richter et al., 2003), the goal was to determine the water level regime

differing the least from the non-regulated conditions, hence the least damageable to the

environment or to the ecological integrity.

On the IJC’s part, this consideration for the ecosystemic impacts in developing a new

plan was indicative of a shift towards environmental sustainability, an unprecedented

change from the conventional engineer’s logic of “mastering” water level fluctuations. An

advocacy group (Public Interests Advisory Group) built from Canadian and American

citizens related with the IJC study also supported in many ways the Environmental TWG

and long term management of the lake Ontario and ST. Lawrence River.

This shift in perspective is especially important at regional/local level where water

management can influence radically the dynamic of a sub-system like Lake St. Pierre.

The case history of the Lake Saint-Pierre area (figure 2), a widening of the St. Lawrence

River serves to better illustrate the ecosystem perspective within a context of water-level

variations.

4. Environmental Issues and Water Level Management: A look at Lake Saint-Pierre

The Lower St. Lawrence River (hereafter referred to as LSL) alternates between wide

(more than 5 km) and fairly shallow (mean depth less than 5 m) fluvial lakes and narrow

(less than 4 km) corridors. Lake Saint-Pierre is the last and largest (more than 300 km2)

of the LSL fluvial lakes before the tidal, fresh water estuarine portion. With over 12 000

hectares of high and low marshes, Lake Saint-Pierre accounts for nearly 80 percent of

LSL marshes (Jean et al. 2002).

Lake Saint-Pierre supports a large population of nesting great blue herons (more than

1300 nests), a major staging area for migratory waterfowl (more than 800 000 ducks and

geese annually) and 167 species of nesting birds (SLC 1996). Permanently submerged

areas and the spring floodplain are home to 13 amphibian species and 79 fishes, many

of which are exploited by sports and commercial fisheries alike. The ecological value of

Lake Saint-Pierre has been recognized by its status as a Ramsar Wetland

(www.ramsar.org), a UNESCO Biosphere Reserve, (www.unesco.org/mab/) and its

inclusion as a protected site under the Eastern Habitat Joint Venture.

Figure 2. Lake Saint-Pierre Area

Despite its special status, Lake Saint-Pierre remains vulnerable to the wide range of

human activities taking place along the LSL shoreline and within the watershed,

including water-level regulation, dredging, shorelines alteration, inflow of nutrients from

neighbouring municipalities and from agriculture, exotic species invasion and climate

change. Human alterations not only exert individual effects on Lake Saint-Pierre

ecosystems, they also interact with each other so that their overall impacts are further

amplified.

The shores of the Greater Montreal area, for example, are heavily urbanized (population

of about 3 million people). They were altered considerably in the 1960s by major

construction projects such as excavation of Montreal Harbour, the St. Lawrence Seaway

and the Louis-Hippolyte-Lafontaine tunnel. Dredged spoil was used to shield the nearby

shoreline, build up jetties and islands, fill in wetlands and develop highways and urban

areas along the shoreline and to create islands for the 1967 World’s Fair (better known

as Expo 67). Overall, about 80 percent of LSL wetlands have been destroyed since the

arrival of the first Europeans in the 16th century; what remains is concentrated mainly

along the shores of Lake Saint-Pierre (Jean et al. 2002).

In addition to direct destruction of wetlands by shoreline encroachment, urban

development brings large amounts of nutrients from domestic wastewaters discharged

into the river after various levels of treatment. Nutrient enrichment to Lake Saint-Pierre

also originates from the tributaries draining the fertile arable lands of the St. Lawrence

River Valley downstream of Montreal.

Over the last 150 years, LSL channel depth was more than doubled (from 4.9 to 11.3 m)

and its width was tripled (from 75 to 245 m), resulting in a 750 percent increase in the

cross-section of the navigation channel linking Montreal and Quebec. In Lake Saint-

Pierre, the presence of the navigation channel concentrates the flow in the central part

of the lake, reduces floodplain connectivity, slows water circulation in the lateral areas

and modifies the hydrological and sedimentary regime in the shallow areas where

wetlands are found.

In the shallow lateral areas of Lake Saint-Pierre, a combination of inflow of sediments

and nutrients from tributaries draining farmland (Figure 3) and slow current speed favour

high productivity by aquatic plants and algae (Vis et al. 2006, Vis 2004). The

accumulated plant biomass in turn further obstructs flow, fostering nutrient assimilation

and the proliferation of filamentous green algae. High plant biomass combined with

near-stagnant waters, high water temperatures and illumination induces large day-night

variations in dissolved oxygen, leading in some areas to sub-optimal habitat conditions

for fish at night. In addition, high algal and bacterial productivity leads to the loss of

nitrate from the water through de-nitrification, which favours the replacement of green

algae by nitrogen-fixing, potentially toxic cyanobacteria. Such phenomena have been

observed since 2003 in Lake Saint-Pierre, which now supports large areas colonized by

filamentous green algae (> 10 km2) and cyanobacteria (> 20 km2).

Figure 3. Lake St. Pierre water masses dynamic

Note. Landsat photo, July 2004. Colors show different water masses and influences from tributaries.

Nutrient enrichment, shoreline encroachment, dredged spoil deposition and alteration of

the natural hydrological regime: these are some of the anthropogenic effects that

destabilize natural plant communities and open the door to the proliferation of certain

invasive species. For example, increased propagation of purple loosestrife (Lythrum

salicaria), reed canary-grass (Phalaris arundinacea) and common reed (Phragmites

australis) was observed under low water-level conditions (i.e. 1995, 1999, 2001) (Hudon

2004). Nutrient enrichment and reduced water flows also foster the proliferation of

submerged (Myriophyllum spicatum) and floating (Hydrocharis morsus-ranae) exotic

plant species. In the future, chronic nutrient enrichment combined with the prospect of

lower water levels and the warmer winter conditions foreseen under climate change

scenarios may facilitate the northward expansion of pest species currently abundant

south of the border, such as water chestnut (Trapa natans).

Water-level variations play a crucial role in maintaining wetlands, where area and

composition vary as a function of climatic variability as well as water level regulation. For

example, over the 1961–2002 period, the total surface area of Lake Saint-Pierre’s

herbaceous emergent wetlands ranged from 11 km2 (high level conditions in 1972) to

128 km2 (low levels in 2001). Wetland species composition, relative abundance and

diversity are influenced by variability in water levels during consecutive growing

seasons. For a given mean level value, wetland plant assemblages differ markedly

whether the multi-year sequence of water levels is rising or falling. The past sequence of

levels shows that Lake Saint-Pierre alternated between three different wetland

configurations, dominated by meadows and open marsh with floating-leaved vegetation

(low level period in the 1960s), scattered tall Scirpus marshes (high level period in the

1970s and early 1980s) and closed marsh with aggressive emergents such as cattails

(since 1996) (Hudon et al. 2005).

Flow regulation and control of ice jams reduce the frequency and magnitude of extreme

high level conditions, which flush out the trapped sediments and organic matter

produced seasonally by plants. Consequently, with chronic flood control, the material

that does enter wetlands is retained longer before high water pulses flush it

downstream, thus contributing to the infilling of shallow areas, which become

progressively more terrestrial. Evidence for this phenomenon is visible in Lake Saint-

Pierre, where cattails, common reeds and willow swamps have colonized previously

submerged areas located immediately downstream of sediment-rich tributaries draining

farmlands. Deposition areas immediately downstream of the Richelieu, Yamaska and

Saint-François rivers became progressively shallower during the low-water level episode

of 1995 and were colonized by terrestrial vegetation which has since persisted and even

expanded. Lake Saint-Pierre is steadily turning into a swamp.

In summary, the response of Lake Saint-Pierre wetlands to human activity demonstrates

their vulnerability to cumulative impacts, profoundly altering the species composition,

diversity and productivity of this large ecosystem.

5. Future challenges to the Sustainability of the S t. Lawrence Ecosystem

Sustainability form the ecosystem side means not only looking at historical interactions

in terms of cumulative impacts as very briefly described for Lake St. Pierre, but also

looking ahead and trying to anticipate potential and/or upcoming issues; thus being able

to react early from a water management perspective. For these issues, this also means

adopting a larger scale and more continental perspective. The ecological integrity of

Lake St. Pierre and more generally the St. Lawrence is now more likely to be threatened

by new, more broadly-based pressures than before. Indeed, the threats now facing the

St. Lawrence are the same ones as those confronting large rivers in heavily populated

areas all over the world.

Water Diversion and Bulk Removals from the Great La kes and the St. Lawrence

River

The issues facing the St. Lawrence River cannot be evaluated without considering the

Great Lakes. Classic divisions among geographic units become less and less relevant in

the light of recent works dealing with the regulation of Lake Ontario and St. Lawrence

waters. Great Lakes issues are St. Lawrence issues: heading the list is the possibility of

water diversions.

Water diversion from the Great Lakes regularly makes the headlines or is the subject of

analyses about the commercial exploitation or export of water (see Morin 2004, for

example). Certainly, this immense water mass has undeniable interest and will become

increasingly appealing with time, as overexploitation of groundwater leads to critical

shortages in the central part of U.S.A. (Glennon 2002).

This issue was not unknown to the IJC8. Back in 1981 it convened the International

Great Lakes Diversion and Consumptive Use Study Board to do an initial assessment of

the anticipated impacts of water diversions and withdrawals. The Board concluded that it

was not possible to reduce the rate of withdrawals to attenuate episodes of low water

levels. lt was suggested that the potential impacts of new diversions or increases in

diversion volumes be monitored.

Nearly 20 years later, in 1999, after a number of diversion projects were proposed, the

IJC produced an interim report on this question9 while requiring that the provinces and

states impose a moratorium on bulk removals of surface and ground water, and that

they act prudently with regard to authorized withdrawals10. In 2000, the final report11

underlined the importance of considering the basin in its entirety as well as the climatic

uncertainty that makes it even more vulnerable. Furthermore, the report indicated that

we should not consider the heavy flows heading toward the river as a loss to uses,

inasmuch as they fulfill an ecological function and that they rejuvenate some habitats (p.

46).

Since 1996, the issue of water management has been the subject of great debate in

Quebec, including questions about privatizing the resource and the rights of farmers.

The animated nature of these debates prompted the provincial government to set up a

public commission tasked with gathering advice and opinions from stakeholders in all

regions of Quebec. The commission presented its recommendations in two reports

focusing on the importance of watershed management showing due consideration for

the environmental sustainability of aquatic ecosystems (see BAPE 2000).

Meanwhile, the federal government ratified an amendment to the Boundary Waters

Treaty Act prohibiting bulk water removal from the Great Lakes basin, with exemptions

for ballast water, humanitarian and safety purposes12. It placed a limit of 50 000 liters

per day on new withdrawals, except for the agri-food sector (water incorporated into

products and bottled water)13. 2001 was also the year the Great Lakes Charter Annex

2001 Implementing Agreements was produced14, promoting an agreement between

Quebec, Ontario, Wisconsin, Ohio, New York, Michigan, Indiana, Pennsylvania,

Minnesota and Illinois. Subsequent discussions were aimed at granting each province

and state bordering the Great Lakes the right to withdraw a certain quantity of water.

This right was touted as a common standard for the conservation and enhancement of

the resource15.

In 2004, the two provinces and eight states concluded an agreement on water removals

which was submitted to the public consultative process. In December 2005, they

formally concluded an agreement that prohibited bulk removals in principle, even while

authorizing them under certain conditions: an exceptional standard volume of 379 000

L/day for a period of 90 days and a regional examination for volumes greater than 19

million litres/day or higher on average over a period of 90 days (s. 201)16. It should be

noted that these limits are subject to a review by all parties. However, in its review of the

recommendations in 2000, the IJC indicated that Indiana, Ohio, Michigan and Wisconsin

had adopted no water conservation programs. There is therefore just cause for concern

that the water rationing approach may be problematic for some of the agreement’s

signatories. Given that this is the case, we must question the prudence of giving the

same rights of withdrawal to other peripheral states.

Despite worries about earlier, pharaonic-scale projects (e.g. the Grand Canal project in

James Bay in the 1960s) which would exert major impacts on basin’s integrity, actual

withdrawals turned out to be much more modest. Quinn and Edstrom (2000) indicated,

for example, that inter-basin diversion projects resulted in a net importation of water to

the Great Lakes. The biggest project to date has been the diversion of the Ogoki River,

where nearly 113 m3/s of water was taken from James Bay and diverted into Lake

Superior. By comparison, in the 1990s, water exports from the Great Lakes basin were

on the order of magnitude of 0.11 m3/s, including the Chicago sanitary canal (from Lake

Michigan to the Mississippi River) and a derivation for the canal between Lake Erie and

the Ohio River. Yet, intra-basin transfers are more important than inter-basin transfers,

exemplified by the 1932 project of 260 m3/s deviated from Lake Erie into Lake Ontario

via the Welland Canal.

For the future, there are serious concerns about the prospect of bulk water exportation,

a pertinent concern worldwide (see Lasserre 2005). However, at the present time for the

Great Lakes and St. Lawrence River, the IJC (2002) has pointed out that transportation

costs would be a major constraint, thus reducing the risks of bulk water exportation.

Large-scale Channel Excavation Threatens the Ecolog ical Integrity of the St.

Lawrence River

The review launched jointly by Canada (Transport Canada) and the U.S. (Transportation

Department) in 2003 of the role of the St. Lawrence Seaway (international and Quebec

sections) may have repercussions on water needs and habitats both17. Projects aimed

at increasing Seaway capacity by deepening it or by widening the locks were officially

excluded18. The recommended approach should rather evaluate the available options for

optimizing the existing infrastructure through maintenance or improvement, as

appropriate, based on projected long-term needs.

Major navigation projects or projects intended to modify navigation must conform to an

established body of legislation dealing with transportation safety (e.g. the Navigable

Waters Protection Act, L.R. 1985, ch. N-22 and related regulations; the International

River Improvements Act, L.R. 1985, ch. I-20), the control of environmental impacts (e.g.

the Canadian Environmental Protection Act, L.R. 1985, ch. 16; the Canadian

Environmental Assessment Act, L.C. 1992, ch. 37) and framework measures applying to

the conservation of large areas (e.g. the Saguenay-St. Lawrence Marine Park Act, and

the Oceans Act, 1996, ch. 31).

This regulatory framework notwithstanding, it should be remembered that the St.

Lawrence has a long history as a gateway to the heart of the continent (Lasserre, 1980)

and that additional development projects, whether in the area of navigation or the

redevelopment and enhancement of shores and urban zones, could emerge in the years

to come.

Integrating Questions of Water Quantity and Quality : A Link Vital

In a 2001 survey19 of 65 organization managers, the relationship between water quantity

and water quality emerged as the second most important issue, just after water

diversions and exports. Although the Great Lakes Water Quality Agreement (GLWQA)

has existed since 1972 (revisited in 1978 and improved by the protocol of 1987)20, the

links between these two aspects have not been systematically developed.

Several monitoring programs regularly report on Great Lakes and St. Lawrence River

water quality, including the State of the Lakes Ecosystem Conference (SOLEC 2004),

the series of Canada-U.S. reports on the application of the GLWQA and the Great Lakes

and St. Lawrence Action Plans. These various monitoring programs deal not only with

the issue of water quality but also with related questions on the state of the ecosystem

and uses of the St. Lawrence21.

The emergence of new water quality problems requires the continuous updating,

integration and dissemination of information in order to better manage the risks to the

environment and to the health of riparian populations. Moreover, linkages between water

quantity and quality must be formalized in order to assess the cumulative effects of

changing water availability on the environment and users, including drinking water

supply and water-based recreational activities.

Climate Change: Accelerating Impacts

Fluctuations in water levels are the natural consequence of climatic variations. Biological

communities have evolved to adapt to seasonal and annual changes in water levels.

Indeed, the diversity and the state of plant communities occurring in wetlands and the

habitats they offer to a variety of invertebrates, amphibians, reptiles, fish, birds and

mammals are strongly influenced by the hydrological regime, each in its own specific

way.

For example, sustained high water levels can lead to the loss of many species of tree

and shrubs. Extreme low levels favour the invasion of riparian plant species. Stabilized

levels favour the dominance of cattails and of dense shallow-water submerged plants.

For fish, the lack of a spring flood also mean loss of access to spawning and reduced

annual recruitment of eggs and larvae. Recent work suggests that the climate of the

Great Lakes-St. Lawrence region is in transition: winters are becoming shorter, the

average annual temperature is on the rise, the ice cover is melting faster, and periods of

intensive rainfall are becoming more frequent (Kling et al. 2003). The anticipated rise in

air temperature (by about 2oC), lengthening of the growing season and increase in the

rate of evaporation (12-17%) is expected to lead in future to a drop of 0.2 to 0.7 m in the

mean water level of the Great Lakes (Lofgren et al., 2002). A recurring deficit in inflows

of water to the Great Lakes basin could in turn translate into a drop of 20 to 40% in

outflows from Lake Ontario to the St. Lawrence River, with an approximate reduction of

1 m in its mean water level at Montreal (Mortsch and Quinn 1996). Most recent

scenarios anticipate a loss of between 4% and 24% of outflows from Lake Ontario

(Crowley, 2003).

In addition to direct effects on ecosystems (Schindler 2001, Mortsch 1998), the long-

term modification of inputs to Lake Ontario will likely impact all socio-economic interest

user groups in Lake Ontario and the St. Lawrence River (NRC 2004, IJC 1999). Climate

effects are not only poorly understood but are also impossible to control, which

emphasizes the need for human adaptation.

The St. Lawrence ecosystem as we know it today is the result of the cumulative effects

of all previous natural and anthropogenic changes to its hydrology, geomorphology,

water quality and species composition. However, climate change scenarios indicate that

additional modifications to the frequency and magnitude of extreme events are likely to

cause further, long-lasting disruptions to the system such as we know it. The climate

factor only adds to the risk exerted by other pressures. By monitoring this factor and its

anticipated effects on the St. Lawrence, we will contribute to developing a capacity for

foreseeing and better reacting to them, as appropriate.

6. Water Availability: An Open-ended Question

Maintenance of adequate water levels and flows in the St. Lawrence River can be

justified by the many public policies adopted over the past 20 years and the major

investments made to date. The more classical regulation perspective has demonstrated

its limits and ecosystem perspective proposes a new framework for decision makers.

Growing recognition of the many goods (exploitable resources) and ecological services

(water storage, erosion control, habitats, nutrient assimilation) provided by the St.

Lawrence River aquatic ecosystems could change the way we value these too often

hidden benefits.

To create the conditions by which the integrity of the ecosystem is maintained, we must

continue to observe environmental trends within the basin and advance research that

characterizes the vulnerability of the ecosystem to cumulative pressures, along with

computer models to better foresee the coming risks. Lake Saint-Pierre is the first area

under observation, but it will not be the last. Indeed, the St. Lawrence is a mosaic of

diversified habitats that must be better understood on an individual basis, certainly, but

also from a more integrated perspective.

The St. Lawrence ecosystem has historically borne many pressures and it will surely

face more in the future, if only from the climatic changes to come. Not only will the

acquisition of new knowledge continue to be necessary, it should better mesh with

decisions made at various levels and in consideration of local and system-wide

concerns. It is expected that the ecology of the system will evolve and challenge even

further human capacity to select the correct adaptation patterns. For future water

management, the sustainability challenge will be to improve the connection between the

historical dynamic of ecosystems and geographical scales of problems and actions.

REFERENCES

BAPE – Bureau d’audiences publiques sur l’environnement. 2000. L’eau, ressource à protéger, à partager

et à mettre en valeur, tome II, rapport de la Commission sur la gestion de l’eau au Québec, no.142. 283

pp.

Carpentier, A. 2003. La régularisation du Saint-Laurent. Le Naturaliste Canadien 127: 102-113.

Crowley, T.J. II. 2003. Great Lakes Climate Change Hydrological Impact Assessment. Technical

Memorandum GLERL-126, IJC Lake Ontario-St. Lawrence River Regulation Study.U.S. Department of

Commerce and National Oceanic and Atmospheric Administration (NOAA), Great Lakes Environmental

Research Laboratory, Ann Arbor, Michigan. 75 pp.

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NOTES

1. It was estimated in the early 1980s that 60% of water already being withdrawn by cities was being

taken from the Great Lakes–St. Lawrence Basin (Pearse et al. 1985).

2. The same year Environment Canada was created.

3. But the issue of federal and provincial jurisdiction sharing seems to come under criticism regarding

water quality, see section II of the Inquiry on federal water Policy report (Pearse et al. 1985).

4. It should be noted that discussions with the U.S. around improving the Seaway first took place in 1895

and that the International Waterways Commission was created in 1903.

5. International Joint Commission. 1998. The International Joint Commission and the Boundary Waters

Treaty of 1909. September, 32 pp.

6. International Great Lakes Levels Board. 1973. Regulation of Great Lakes Water Levels. Report to the

International Joint Commission; International Joint Commission. 1993. Levels of Reference Study;

International St. Lawrence River Board of Control. 1997. An Updated Regulation Plan for the Lake

Ontario-St. Lawrence River System.

7. The study area covers the 4350 km of shore from the western tip of Lake Ontario (Niagara Falls,

Ontario and New York) to Trois-Rivières, Quebec, where the impacts of regulating water-level variations

are felt. This five-year, $30-million (CAN) study was funded equally by the federal governments of Canada

and the United States.

8. The city of Chicago was responsible for the first large-scale diversion, in 1900. Water was withdrawn

from the Great Lakes to facilitate the flow of wastewater toward the Mississippi River.

9. International Joint Commission. 1999. Protection of the Waters of the Great Lakes. Interim Report to

the Governments of Canada and the United States. August 10, 1999.

10. “IJC recommends moratorium on bulk removals and sales of Great Lakes water.” Press release dated

August 18, 1999.

11. International Joint Commission. 2000. Protection of the Waters of the Great Lakes. Final Report to the

Governments of Canada and the United States. February 22, 2000.

12. Accord for the Prohibition of Bulk Water Removal from Drainages Basins.

13. International Joint Commission. 2004. Protection of the Waters of the Great Lakes, Review of the

Recommendations in the February 2000 Report.

14. Great Lakes Charter: Principles for the Management of Great Lakes Water Resources. February 11,

1985 (signatures of Provincial premiers and State governors affixed). Great Lakes Charter Annex,

supplementary agreement to the Great Lakes Charter, June 18, 2001 (with signatures of Canadian

provincial premiers and U.S. state governors).

15. International Water Uses Review Task Force. Protection of the Waters of the Great Lakes: Three-year

Review. November 8, 2002. International Joint Commission.

16. Great Lakes-St. Lawrence River Basin Sustainable Water Resources Compact. December 13, 2005.

17. Memorandum of Cooperation between the Minister of Transport of Canada and the U.S. Department

of Transportation. Signed in Washington by David M. Collenette and Norman Y. Mineta. May 1, 2003.

2 pp.

18. Great Lakes-St. Lawrence Seaway Study. Stakeholder Engagement Document. Joint Canada-U. S.

study. April 2004.

19. Hertig, J., J.V. DePinto, S. Bocking, J.V. Stone, and P. McIntyre. 2001. Great Lakes Science and

Policy: Strengthening the Connection. Report of a study on policy issues related to the Great Lakes. Joyce

Foundation.

20. “Great Lakes Water Quality Agreement: Quick Facts.” Available on the Environment Canada Web site:

<http://www.on.ec.gc.ca/greatlakes/default.asp?lang=En&n=EE1B7E6A-1>.

21. A series of fact sheets on monitoring the state of the St. Lawrence is now available on line

at <www.slv2000.qc.ca>. The first fact sheets in the series date back to 2003.