Corps de l’article

Freshwater ecosystems face serious threats[1]. Owing to loss of habitat and biodiversity, freshwater ecosystems are generally in far worse condition than forests, grasslands or other terrestrial ecosystems[2]. Extinction rate for freshwater fauna is estimated to be a thousand times higher than background rate, and future extinction rate is expected to be five times higher for freshwater fauna than for terrestrial species[3].

Legal protection of freshwater ecosystems and their various components is crucial[4]. Natural water flows and hydrologic regimes in rivers and watersheds fulfil essential functions sustaining freshwater ecosystems and must be preserved from unacceptable anthropogenic degradation[5]. This necessity is recognised in Québec, and the provincial government undertook to establish rules governing flow alteration in 2002[6]. Such rules are bound to play a fundamental role for freshwater conservation in the context of increasing hydrological variability and resource exploitation. On one hand, various record low flows in Québec rivers have been established during the spring of 2010 due to an extremely mild winter and precipitations 20 percent below average[7]. On the other hand, a recent governmental initiative fostering small-scale hydro-power development resulted in the initiation of 31 projects altering the hydrologic regime on various rivers to the dissatisfaction of environmental NGOs[8].

Against this background, the development of a legal framework preserving environmental flows has recently become apparent in Québec. This article first contextualises issues related to environment flows (1), and then details the emergence of a regime for environmental flow protection in Québec law (2).

1 Perspectives on environmental flow protection

The object of this section is to present principles of eco-hydrology that establish the need for allocating water to environmental uses (1.1), and offer examples of legal approaches to environmental flow protection in different jurisdictions (1.2.)[9].

1.1 Principles of eco-hydrology : Environmental flow protection as a necessity

Hydrologic regimes in surface waters are generally described through a series of characteristics related to magnitude, rate of change, frequency, timing, duration and inter-annual variability[10]. Flow magnitude refers to the quantity and velocity of water in a river channel. Variation in flow magnitude depends on water inputs from precipitations and aquifers, the alternation between dry and wet periods generating baseflows and peak discharges. The speed at which flow magnitude varies is described through the rate of change and depends in part on the intensity and duration of rainfalls as well as on groundwater resurgence. Regular precipitation patterns can cause recurrent flooding and minimum flows at certain times of the year, leading to seasonal variations described through frequency and timing. Finally, inter-annual variability refers to flow regimes that change from year to year due to irregular precipitation patterns.

Hydrologic regimes are identified as the master variable among the dynamic processes related to freshwater ecosystems[11]. Natural water flows constitute the template upon which evolution forges survival strategies and determine the composition, abundance and arrangement of biological communities found in pristine freshwater ecosystems[12]. The various characteristics of hydrological regimes perform functions that influence the viability, reproductive capacity and sustainability of various freshwater species[13]. For example, modification of the timing, frequency or duration of floods can eliminate spawning or migratory cues for fish, or reduce access to spawning areas[14]. According to the dominant scientific paradigm, the alteration of natural flow characteristics degrades aquatic ecosystem integrity[15].

Human activities cause significant alterations of natural water flows that impact aquatic ecosystems[16]. Although changes in land uses, wildlife exploitation and pollutant discharges can all significantly degrade freshwater ecology, natural flows are directly affected by specific quantitative anthropogenic water uses[17]. For example, excessive water withdrawals and inter-basin water transfers can induce stream channel dewatering and river closure, which may result in loss of biodiversity, reduced surface water quality and extensive damage to aquatic ecosystems[18]. In particular, dams and other water impoundments have the most pervasive impacts on water flows because they can modify all characteristics of surface hydrologic regimes[19]. Dams can alter natural patterns in water temperature, sediment transport, nutrient flows, river channel morphology, floodplain vegetation community, as well as connectivity between upstream reaches and estuaries, thereby altering aquatic ecosystem quality[20].

In this context, the unallocated flow of water intentionally preserved in rivers and streams further to the prescriptions of management frameworks is identified as environmental flow. Quantitative water uses directly affecting natural water flows must be regulated to prevent unacceptable freshwater ecosystem degradation. Because all quantitative anthropogenic water uses alter characteristics of natural hydrologic systems, environmental flow protection does not require restoring hydrologic regimes to pristine condition but depends on a political process through which societies establish a balance between resource exploitation and conservation[21].

1.2 Examples of legal frameworks for environmental flow protection

Environmental flow protection is a feature of a growing number of legal frameworks for water resources management in various jurisdictions. Water scarcity is a driver for the development of legal frameworks allocating water to ecosystem uses. In Australia, both commonwealth and state water law foster environmental flow protection. At commonwealth level, the Water Act provides a framework regulatory structure that requires the scheduling and delivery of environmental water to maintain ecosystem functions and biodiversity with specific regards to the interstate Murray-Darling basin[22]. At state level, legislation such as the Water Management Act impose legal duties on governments to make management plans establishing rules with respect to environmental flows in order to protect water sources and ecosystems[23]. Under such plans, water quantities in excess of specific volumetric long-term average annual extraction limits may not be withdrawn for any purpose[24]. Similarly faced with an arid climate, South African law incorporates environmental flow requirements through an ecological reserve from which water abstraction is prohibited in order to protect aquatic ecosystems[25]. Although the reserve still remains undetermined, the development of operational rules for environmental flow requirements in some South-African basins can entail variable withdrawal curtailments that are dependent on natural variations in river flows[26].

As increasing water resources exploitation generates growing water stress, environmental flow protection has also emerged in the legal frameworks of temperate jurisdictions. In Switzerland, the Loi fédérale sur la protection des eaux aims at maintaining appropriate flow regimes through a permit system for water withdrawals : a water use that substantially affects the flow of a watercourse when combined with other uses may be permitted if the residual flow in the watercourse is not reduced under a certain quantitative level[27]. Transposition of the Water Framework Directive in the national legal order of some European jurisdictions such as Scotland results in the development of state-of-the-art water resources management regimes that aim at restoring aquatic ecological quality by setting reference conditions for various characteristics of natural flows[28]. Regulations implementing the Scottish Water Environment and Water Services Act identify different ecological quality levels based, inter alia, on detailed aspects of hydrological regimes such as water volumes in daily river flows and natural lake outflows[29]. The conjunction of river basin planning with a licensing regime covering quantitative anthropogenic water uses is intended to ensure good ecological status for aquatic ecosystems notably through the preservation or restoration of some environmental flows[30].

In Canada, legal provisions protecting aspects of hydrological regimes have also emerged in some provincial jurisdictions[31]. The following section analyses the legal framework pertaining to environmental flow protection in Québec.

2 The legal framework for environmental flow protection in Québec

In Québec, water is relatively abundant. Unlike more arid Canadian jurisdictions such as Alberta where water resources in some basins are fully allocated since 2004, Québec’s hydrology generally ensures minimum low flows to sustain environmental water uses without requiring restrictions on abstractions for agricultural or industrial purposes[32]. In this context, dams and impoundments have particularly significant impacts on environmental flows relative to other water uses that directly affect water quantity such as abstractions and diversions[33]. Given the specificity of the management framework applicable to water impoundments as well as the large number of dams in Québec’s rivers due to reliance on hydro-power production, this section firstly details how the regulation of impounding work construction and operation can preserve downstream residual environmental flows (2.1), and secondly, examines the effect of the legal regimes governing other water uses that have a direct impact on water quantity such as withdrawals and diversions (2.2.)[34].

2.1 The regulation of flows downstream of dams and impoundments

2.1.1 The general impact of administrative authorisation regimes

In Québec, the construction and operation of dams and other impoundments are subject to a variety of authorisation regimes under discretionary administrative power in both provincial and federal law that aim, inter alia, at preserving the environment or one of its component from impacts generated by human activities[35]. Within their respective domains, these regimes can protect natural water flows. An impoundment project altering the hydrologic regime may not be authorized because it has unacceptable consequences for the environment, a conservation habitat or a protected zone. In many cases, a projected impoundment may also be authorised under specific conditions that minimise or compensate resulting environmental impacts, among which alterations to environmental flows.

In provincial legislation, various preventive environmental impact assessment regimes provided by the Environment Quality Act that submit water impoundments projects to preliminary governmental and ministerial authorisations have a particular importance[36]. While all water storage projects are considered for inclusion under the assessment regimes applicable in the James Bay region and in the territory north of the 55th parallel, only the construction and operation of a dam or a dike impounding a reservoir or a lake that exceeds a specific surface as well as the construction and operation of a hydroelectric station with a capacity that exceeds 5 MW are subject to preliminary governmental authorisations in southern Québec[37]. If the impoundment project is authorised, the competent authority may impose binding conditions on its construction and operation to preserve some characteristics of downstream flows[38]. In addition, other authorisation regimes generally applicable to impoundment projects can impose conditions with respect to downstream flows[39]. Although their scope is necessarily limited, authorisation regimes applicable to dam projects in protected natural habitats may also play a role in restricting alterations to environmental flows[40].

Since 1999, the Politique des débits réservés écologiques pour la protection du poisson et de ses habitats defining reserved ecological flows to maintain normal fish life-cycles applies to impoundment projects subject to the provincial authorisation regimes mentioned[41]. Scientific methods identified in the Politique serve to determine the minimum modulated water flows necessary to ensure fish passage and conserve the pre-existing quantity and quality of fish habitats after the alteration of downstream hydrologic regimes by the projected impoundments[42]. Reserved flows thus determined must be protected in principle. However, the Politique indicates that residual flows inferior to reserved flows may be accepted when an impoundment project would not otherwise be economically or technically feasible[43]. In such a case, lost fish habitats must be compensated elsewhere to ensure no overall net loss. Authorisations granted for dams and impoundments since 1999 evidence that the Politique is considered[44].

By contrast, no specific normative framework prescribes reserved ecological flows downstream of impoundments at the federal level. Nevertheless, some legal regimes can preserve characteristics of environmental flows[45]. The International River Improvements Act explicitly prohibits the construction, operation or maintenance of a dam, reservoir or other work that alter natural water flow from any place in Canada to any place outside Canada[46]. The significance of this prohibition is considerably reduced by its narrow scope, by various exceptions thereto, and by the possibility of obtaining licences[47]. A less explicit but broader regime for protecting environmental flows from impoundments derives from dispositions regulating fish passage under the Fisheries Act[48]. According to the FA, the Minister of Fisheries and Oceans (hereinafter “MFO”) may determine that dams or dikes must be provided with passes or canals to be maintained and supplied with sufficient quantities of water for the free passage of fish[49]. Also, the MFO may determine that sufficient water flows over instream obstacles and into the river downstream must be provided for the unimpeded descent of fish and for the flooding of spawning grounds[50]. Under this regime, a minimum flow order can, even retrospectively, require water releases from a reservoir equivalent to 45 percent of the natural river flow at all time[51]. Finally, although a federal regime submits impoundment projects to a procedure for environmental impact assessment, the evaluation of alterations to hydrological characteristics such as flow rate and current velocity proceeds on a case-by-case basis[52].

2.1.2 The regulation of water flows in the St. Lawrence River

Regulation of the St. Lawrence River significantly impacts provincial freshwater ecosystems and sectoral water usages[53]. A particularised study of the institutional framework regulating water levels in the St. Lawrence River reveals the importance of a specific legal regime that affects environmental flows in Québec and that connects provincial hydrology to a transboundary watershed[54].

The St. Lawrence River plays a fundamental role in Québec’s waterscape for both anthropogenic and environmental water uses. A third of Québec’s territory and 97 percent of Québec’s population are located in its drainage basin[55]. The River provides 40 percent of the province’s annual water recharge and 45 percent of Québec’s annual water withdrawals[56]. It supplies drinking water for three million people in some 100 riparian municipalities[57]. The St. Lawrence River also supports an enormous aquatic ecosystem characterised by rich fauna and flora biodiversity as well as significant species endemism in fish and bird communities[58]. A reported 80 percent of the areas protected under the ARCDW are located within the St. Lawrence River riparian zone[59].

The St. Lawrence River is managed through a transboundary legal regime as the emissary of the North American Great Lakes Basin[60]. One of the cornerstones of this transboundary regime, the Boundary Waters Treaty between Canada and the United States of America, characterises the St. Lawrence River as boundary waters[61]. The Boundary Waters Treaty generally prohibits uses, obstructions or diversions of boundary waters affecting the natural level or flow of boundary waters, except further to an authorization from Canada or the United States within their respective jurisdictions and with the approval of the International Joint Commission (hereinafter “IJC”)[62]. The principles that guide IJC’s discretionary power to approve a project affecting the natural level of boundary waters establish a preference towards water uses for domestic purposes, then navigation and finally power generation and irrigation, but ignore the need to ensure sufficient water quantity and quality for wildlife and environmental protection[63]. IJC’s orders of approval may include conditions and criteria governing the construction and operation of a project.

Since the Boundary Waters Treaty authorization regime entered into force, the IJC has received a number of applications for projects with a potential impact on the level and flow of the St. Lawrence[64]. One of these projects, sponsored by the governments of Canada and the United States and approved by the IJC, has a significant impact on the flow of the St. Lawrence River in Québec since the late 1950s[65]. The operation of the approved dams and locks, among which the Moses-Saunders hydropower dam near Cornwall, is adjusted weekly to regulate water levels by applying thirteen regulation criteria contained in Plan 1958-D that relate to the stabilisation of water levels in Lake Ontario, maintenance of minimal levels for navigation, facilitation of energy production, and minimisation of flooding risks[66]. A series of operating curves in Plan 1958-D covers different trends in the water supply conditions for Lake Ontario and dictates that if the water supplies to the lake are high, for example, the curve with a higher supply indicator will be used to determine the outflows, and vice versa[67].

As a result, the operation of regulation infrastructure is the second determining factor for water levels in the fluvial portion of the St. Lawrence River after natural precipitations variations over the Great Lakes and Ottawa River watersheds[68]. When hydrological conditions correspond to hydrological data from the 1860-1954 reference period that was used to produce Plan 1958-D, flow regulation results in the reduction of flooding-related issues on the shores of Montréal in Lake St. Louis, in the increase of St. Lawrence River baseflows, and in the reduction of ice jams[69]. However, as hydrological conditions since 1963 have diverged widely from those of the 1860-1954 reference period, derogations from the norms contained in Plan 1958-D have occurred almost 50 percent of the time and the discretionary regulation of outflows has aimed at minimising detriments rather than maximising advantages for stakeholders downstream of the Moses-Saunders dam[70].

The regulation of water levels in the St. Lawrence River under Plan 1958-D has significantly affected the distribution and composition of species assemblages as well as the functioning of biotic processes in stream and riparian areas[71]. In response to environmental concerns and stakeholders dissatisfaction, the International Lake Ontario-St. Lawrence River Study Board was mandated by the IJC to formulate replacement options for Plan 1958-D and produced three candidate plans entitled A+, B+ and D+ in 2006[72]. Plan B+ provides greater environmental benefits than Plan A+ or Plan D+ as well as greater potential ecosystem improvements compared with Plan 1958-D on Lake Ontario and the upper St. Lawrence River, but all candidate plans show almost no environmental benefits below the Moses-Saunders dam[73]. At the moment, selection of a new plan by the IJC is still under review and regulation of the St. Lawrence River proceeds under status quo.

2.2 Regimes applicable to water withdrawals and diversions

2.2.1 Regimes contributing to environmental flow protection

Québec law contains measures affording some protection to environmental flows from water withdrawals and diversions. In some cases, the legal framework for water resources apportionment explicitly preserves water for aquatic ecosystem use. For example, the provincial regime for wildlife management individually caps agricultural withdrawals from a watercourse in a protected fish habitat to no more than 15 percent of the water flow[74]. However, streamflow protection is still mostly indirect and piecemeal, as it results from the ad hoc application of various sectoral authorisation regimes regulating withdrawal or diversion projects with potential impacts on the environment or one of its components, among which hydrologic regimes[75]. For example, under the EQA, a general regime within the ambit of the Politique applies to water withdrawal or diversion projects altering water flows, but the required preliminary ministerial authorisation cannot impose conditions to mitigate or compensate negative environmental impacts and the Politique has never justified the refusal of an authorisation[76]. Likewise, regimes with localised application domains may indirectly foster environmental flow protection although their effective impact remains unclear : the federal framework for protected areas restricts potential alterations to hydrologic regimes that result from withdrawals or diversions without explicitly reserving water for ecosystem uses[77].

In this context, two regimes warrant specific attention with respect to environmental flows, the first due to its breadth and the second due to its object. Firstly, the protection of fish habitat by the FA constitutes a prominent example of an authorisation regime regulating withdrawal or diversion projects with potential impacts on environmental flows[78]. Under this regime, the harmful alteration, disruption or destruction of fish habitat is prohibited unless authorised by the MFO[79]. Harmful alterations or destructions of fish habitat are generally considered to result from a variety of causes, among which channel diversions as well as changes in the hydrology or hydraulics of a watercourse where the remaining flow may be below that required for successful utilisation of the habitat due to water withdrawal[80]. Applications for authorisation must describe fish habitat conditions that will prevail after project completion with respect to, inter alia, water width, depth, flow, velocity, and water level recurrence intervals[81]. Assessments of projected fish habitat degradation are performed on a case by case basis as there is no administrative guideline indicating generally acceptable characteristics for residual flows. However, the Department of Fisheries and Oceans might prepare a directive on this issue that would rely on the natural flow paradigm[82].

Secondly, the legal framework for groundwater management provided by the Groundwater Catchment Regulation constitutes an apportionment regime akin to regulated riparianism which explicitly acknowledges aquatic ecosystems water uses[83]. Since 15 June 2003, groundwater withdrawal projects with a daily capacity of 75 m3 or more must be authorised by the MSDEP[84]. When considering whether to authorise a groundwater withdrawal, the MSDEP’s discretionary power is guided by criteria enunciated in the GCR[85]. According to these criteria, abstractions should not draw groundwater in excessive amounts considering the resource’s availability, and negative impacts caused by groundwater abstractions on watercourses and bodies of water as well as related ecosystems should be minimised. Hydrogeological studies accompanying applications for authorisation identify the possible environmental impacts of proposed withdrawals and provide detailed information with respect to the criteria guiding ministerial power[86]. In particular, hydrogeological studies indicate whether groundwater withdrawals degrade environment quality and significantly affect low flows in wetlands, watercourses or bodies of water, thereby damaging ecosystems[87]. Furthermore, authorisations under the GRC are generally valid for 10 years[88].

2.2.2 Environmental flow under the Act to affirm the Collective Nature of Water Resources

Although not yet in force, a framework for the quantitative allocation of water resources established by the ACNWR arguably develops and extends the approach initiated under the GRC[89]. Some features of this new framework for water allocation are relevant to environmental flow protection because the ACNWR takes aquatic ecosystem water uses into consideration[90].

Under the ACNWR, underground and surface water withdrawals except impoundments are subject to a detailed authorisation regime[91]. The discretionary power to authorise a withdrawal must be exercised so as to ensure the protection of water resources[92]. Priority is granted to satisfying public health, sanitation, civil protection and drinking water supply needs, but the decision to authorise a withdrawal must also aim to reconcile the protection needs of aquatic ecosystems[93]. Environmental impacts as well as the availability and distribution of water resources must be taken into account, with a view to satisfying or reconciling current and future needs of different water uses[94]. As a result, the criteria guiding the discretionary power to authorise water withdrawals impose that ecosystems water uses be considered. Although environmental flow requirements remain undefined under this regime, aquatic ecosystem water uses materialise within the legal order as a potential constraint on anthropogenic uses, thereby reflecting the inherent competition between concomitant uses of a finite resource[95].

Acknowledging the inherent variability of local hydrological flows and the increasing unpredictability of the water supply in a context of climate change, the ACNWR regime also places restrictions on the length of some water uses. Ministerial authorisations other than those for the supply of drinking water to a waterworks system operated by a municipality are valid for a period of 10 years[96]. If an authorisation is renewed, different conditions, restrictions or prohibitions may be imposed on the withdrawal, notably to ensure greater protection for the environment, aquatic ecosystems and wetlands[97]. Moreover, even a valid authorisation may be limited, temporarily curtailed or cancelled when a withdrawal presents a serious risk for aquatic ecosystems[98]. As a result of these temporal restrictions, risks related to water supply variability are shared more evenly between anthropogenic uses and aquatic ecosystems relying on environmental flows[99].

Conclusion

A multitude of authorisation regimes in provincial and federal law regulate projects with potential impacts on environmental flows without explicitly referring to instream water levels or water allocations to ecosystems. The protection afforded to environmental flows under these regimes may stem from the administrative power to refuse authorisations or impose conditions on the construction and operation of projects altering natural hydrology in order to prevent, minimise or compensate potential environmental damages. Such skein of partially overlapping regimes offers a mostly indirect and fragmented protection to environmental flows against quantitative anthropogenic water uses, discounting fundamental linkages in the hydrologic cycle and aquatic ecosystems. A certain degree of fragmentation is inevitable given the size and geographical situation of the St. Lawrence River watershed, but further integration of the water resources management framework could foster the preservation of water allocations to ecosystems[100].

In this context, the adoption of the Politique des débits réservés écologiques pour la protection du poisson represents a significant step towards a more comprehensive framework for environmental flow protection. However, the Politique remains an imperfect tool. First, it does not apply to water uses anterior to 1999 and cannot serve to restore aquatic ecosystem quality compromised by an anterior use other than on a voluntary basis. Second, its implementation is discretionary, and alterations considered unacceptable under the Politique such as complete river-flow cut-offs are authorised in practice. The economic and technical feasibility exclusion ensures that any type of environmental flow alteration can be authorised, thus significantly reducing the Politique’s effectiveness as a normative instrument. Third, the Politique focuses exclusively on the provision of water for fish and neglects the effects of flow alteration on other components of the biotic assemblages integral to aquatic ecosystem quality[101]. Fourth, reliance on the principle of compensation for lost habitat can lead to the acceptance of important shifts in ecosystem species composition[102]. For example, loss of habitats suitable to species adapted to high flow velocity can be considered acceptable under the Politique because balanced by gains in habitats for species adapted to standing water. However, repetition of such a compensation project after project may homogenise fish biodiversity. Finally, the discrete implementation of the Politique through ad hoc authorisations under various regimes may hinder the capacity to address cumulative impacts on environmental flows and ecosystems. This risk is particularly significant when rivers earmarked for out-of-site habitat compensation are not identified during the authorisation process for specific projects[103].

As a result, fulfilment of the governmental undertaking to extend and improve environmental flow protection remains essential. The emerging recognition of allocations to aquatic ecosystems in the legal framework for quantitative water resources apportionment constitutes a progress in this direction. Such recognition, initiated by the GCR and explicited under the ACNWR, could be further substantiated by the development of operational rules to determine damages sustained by or restorations measures for water resources in the context of an action by the Attorney General[104]. In this context, exercise of the state’s police power to require the restoration of water resources could be construed as the materialisation by proxy of aquatic ecosystems rights against anthropogenic abuses.

However, progress under the ACNWR does not address gaps in environmental flow protection that result from the fragmentation of the provincial water allocation framework in two increasingly independent regimes applicable to impoundments on one hand and withdrawals on the other. Water stress caused by water resources exploitation and heightened hydrological variability would vindicate a comprehensive regime addressing water allocation issues between all anthropogenic and ecosystem uses. The reform and improvement of the Politique is a temporary but essential palliative as long as impoundments remain excluded from the general management regime for water withdrawals. The finalisation of a new regulation plan for St. Lawrence River flow after more than a decade of negociation must also be prioritised to adequately protect Québec’s freshwater ecosystems as climate change is expected to significantly alter the Great Lakes hydrology.