*Article* **Twenty-First Century Science Calls for Twenty-First Century Groundwater Use Law: A Retrospective Analysis of Transboundary Governance Weaknesses and Future Implications in the Laurentian Great Lakes Basin**

**Khafi Weekes 1,\* and Gail Krantzberg <sup>2</sup>**


**Abstract:** How has groundwater use been historically governed by the binational to municipal government levels across the Laurentian Great Lakes Basin (GLB)? To what extent have they contemplated the physical–environmental requirements to maintain aquifer storage in devising policies and making decisions governing groundwater use? Although it is amongst the largest freshwater stores in the globe, cases of groundwater shortages are increasingly being reported across GLB communities, raising questions on the fitness of governance approaches to maintain groundwater storage (GWS) with growing climate and human pressures. Applying retrospective analytical methods to assess the century-old collaboration of the United States and Canada to maintain GLB water quantities, we characterize long-term trends and undertake systematic diagnosis to gain insight into causal mechanisms that have persisted over the years resulting in current GWS governance gaps. We reveal the surprising prominence of policies originally intended to safeguard surface water quantities being used to govern groundwater use and thereby maintain GWS. We also connect these, based on sustainable aquifer yield theory, to growing groundwater insecurity in the Basin's drought-prone and/or groundwater-dependent communities. Based on deep understanding of long-standing policy pathologies, findings inform transboundary GWS governance reform proposals that can be highly useful to multiple levels of government policymakers.

**Keywords:** groundwater storage; groundwater use; multilevel governance; agreement; transboundary basins; retrospective analysis; United States; Canada

#### **1. Introduction**

With estimates ranging from 5585 km<sup>3</sup> to 4000 km<sup>3</sup> [1], groundwater accounts for roughly 20% of water stored in the Laurentian Great Lakes Basin (GLB). Groundwater fluxes maintain habitats and baseflows to tributaries of the five (5) Great Lakes [2]. It has also become increasingly vital for society, supporting the USD 6 trillion regional economy [3] of the eight (8) US states and the Canadian province of Ontario that are within the GLB's hydrological boundaries (Figure 1).

**Citation:** Weekes, K.; Krantzberg, G. Twenty-First Century Science Calls for Twenty-First Century Groundwater Use Law: A Retrospective Analysis of Transboundary Governance Weaknesses and Future Implications in the Laurentian Great Lakes Basin. *Water* **2021**, *13*, 1768. https:// doi.org/10.3390/w13131768

Academic Editors: Sharon B. Megdal and Anne-Marie Matherne

Received: 16 March 2021 Accepted: 21 June 2021 Published: 26 June 2021

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**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

**Figure 1.** States and provinces within the Laurentian Great Lakes Basin hydrological boundary [4]. **Figure 1.** States and provinces within the Laurentian Great Lakes Basin hydrological boundary [4].

Rising populations with their attendant water demand and land use changes, coupled with climate change [5], are driving an emerging problem of persistent groundwater storage (GWS) decline. At the Basin scale, long-term satellite monitoring estimates an average GWS loss of 3.8 ± 2.3 km3/year [6]. Though this rate of decline pales in comparison to the overall water-richness of the GLB, the globe's largest surface freshwater store, much of it occurs in drought-prone and/or groundwater-dependent communities. Located further inland, these locales are without ready access to Great Lakes' waters, and are becoming increasingly water insecure [7]. These trends are emerging as GWS—the volume of water that an aquifer holds at any given time within its voids and interstices—is fundamentally limited by an aquifer's storage capacity, which is based on its unique geometry and geophysical attributes [8]. While the quantity of GWS can fluctuate seasonally, as it is a derivative of a predefined rate of inflow from artificial recharge and/or precipitation, and outflow via natural discharge to surface water bodies and/or pumping, it can be permanently drawn down if subject to long-term overuse and reduction of recharge with climate change and land uses that increase impermeable surfaces [8]. Rising populations with their attendant water demand and land use changes, coupled with climate change [5], are driving an emerging problem of persistent groundwater storage (GWS) decline. At the Basin scale, long-term satellite monitoring estimates an average GWS loss of 3.8 <sup>±</sup> 2.3 km3/year [6]. Though this rate of decline pales in comparison to the overall water-richness of the GLB, the globe's largest surface freshwater store, much of it occurs in drought-prone and/or groundwater-dependent communities. Located further inland, these locales are without ready access to Great Lakes' waters, and are becoming increasingly water insecure [7]. These trends are emerging as GWS—the volume of water that an aquifer holds at any given time within its voids and interstices—is fundamentally limited by an aquifer's storage capacity, which is based on its unique geometry and geophysical attributes [8]. While the quantity of GWS can fluctuate seasonally, as it is a derivative of a predefined rate of inflow from artificial recharge and/or precipitation, and outflow via natural discharge to surface water bodies and/or pumping, it can be permanently drawn down if subject to long-term overuse and reduction of recharge with climate change and land uses that increase impermeable surfaces [8].

GWS governance, involving planning, coordinating, policy making, implementation, and monitoring of policy outcomes [9], provides the means by which groundwater use may be managed, and socio-environmental stressors on GWS addressed. Normatively, long-term GWS decline indicates that governance may be ill-suited to the physical–environmental sustainability needs to maintain GWS. When governance effectuates actions resulting in increased and/or long-term stability of GWS and optimal economic development, it can be considered sustainable [10,11]. In these cases, consideration is placed on maintaining sustainable aquifer yield—the volume of groundwater that can be withdrawn from aquifer systems that avoids unacceptable environmental, socio-economic, and legal consequences [12]. Determining sustainable yield requires strong science–policy alignment as policymakers must consider the water balance of the overall hydrological system, uncertainties in quantifying GWS with spatial and temporal variation, and how human uses can impact GWS over time [12]. GWS governance, involving planning, coordinating, policy making, implementation, and monitoring of policy outcomes [9], provides the means by which groundwater use may be managed, and socio-environmental stressors on GWS addressed. Normatively, long-term GWS decline indicates that governance may be ill-suited to the physical– environmental sustainability needs to maintain GWS. When governance effectuates actions resulting in increased and/or long-term stability of GWS and optimal economic development, it can be considered sustainable [10,11]. In these cases, consideration is placed on maintaining sustainable aquifer yield—the volume of groundwater that can be withdrawn from aquifer systems that avoids unacceptable environmental, socio-economic, and legal consequences [12]. Determining sustainable yield requires strong science–policy alignment as policymakers must consider the water balance of the overall hydrological system, uncertainties in quantifying GWS with spatial and temporal variation, and how human uses can impact GWS over time [12].

Given the GLB's transboundary basin settings, policies and decision-making standards impacting GWS (also known as the "GWS governance framework") are contained in binational-to-municipal-level statutes, voluntary agreements/regulations, common law, and treaties [13]. Per North American institutional historicism, the most important to maintaining GWS are those directly controlling groundwater use: out-of-basin diversions, pumping rates, allocation, conservation, consumption, and withdrawals [14]. Economic policies are also key, creating fiscal deterrents and/or incentives under which groundwater use decisions are made [15]. Environmental safeguards are another aspect, with requisites for data collection and monitoring as well as technical/environmental standards for well construction and pumping [16]. Given the GLB's transboundary basin settings, policies and decision-making standards impacting GWS (also known as the "GWS governance framework") are contained in binational-to-municipal-level statutes, voluntary agreements/regulations, common law, and treaties [13]. Per North American institutional historicism, the most important to maintaining GWS are those directly controlling groundwater use: out-of-basin diversions, pumping rates, allocation, conservation, consumption, and withdrawals [14]. Economic policies are also key, creating fiscal deterrents and/or incentives under which groundwater use decisions are made [15]. Environmental safeguards are another aspect, with requisites for data collection and monitoring as well as technical/environmental standards for well construction and pumping [16].

Researchers have long posited that the GWS governance framework may be unfit for purpose in high-groundwater-stress contexts of the GLB [17–22]. They concur on its inadequate consideration of sustainable yield, in particular its insufficient science-based guidelines and incentives promoting conservation and efficient uses that reflect the unique physical–environmental requirements of aquifers to maintain GWS. Growing cases of GWS decline across the basin highlight the need for binational-to-municipal levels of government within the hydrological boundaries of the GLB to provide policies and decision-making standards guiding management actions [23] that address human and climate drivers of GWS depletion [20]. It also presents an opportunity for the establishment of proactive multilevel governance measures designed to halt further proliferation of this problem. Retrospective analysis of historical governance characteristics has proven useful to deepen understanding of present-day policy gaps, and confirm inferences of why policies have led to current environmental outcomes [24]. Using this analytical approach, we deconstruct the historical evolution of GWS governance, deducing features and inferring causal linkages that are likely to have culminated in growing cases of GWS decline and gaps in the current GWS governance framework. Findings are used to proffer recommendations of governance reforms addressing the growing specter of groundwater insecurity deepening in vulnerable locales. Researchers have long posited that the GWS governance framework may be unfit for purpose in high-groundwater-stress contexts of the GLB [17–22]. They concur on its inadequate consideration of sustainable yield, in particular its insufficient science-based guidelines and incentives promoting conservation and efficient uses that reflect the unique physical–environmental requirements of aquifers to maintain GWS. Growing cases of GWS decline across the basin highlight the need for binational-to-municipal levels of government within the hydrological boundaries of the GLB to provide policies and decision-making standards guiding management actions [23] that address human and climate drivers of GWS depletion [20]. It also presents an opportunity for the establishment of proactive multilevel governance measures designed to halt further proliferation of this problem. Retrospective analysis of historical governance characteristics has proven useful to deepen understanding of present-day policy gaps, and confirm inferences of why policies have led to current environmental outcomes [24]. Using this analytical approach, we deconstruct the historical evolution of GWS governance, deducing features and inferring causal linkages that are likely to have culminated in growing cases of GWS decline and gaps in the current GWS governance framework. Findings are used to proffer recommendations of governance reforms addressing the growing specter of groundwater insecurity deepening in vulnerable locales.

#### **2. Materials and Methods 2. Materials and Methods**

We applied causal process tracing (CPT)—a qualitative, retrospective analytical technique useful for deducing change and causation within a temporal sequence of events [25]. Per Figure 2, CPT operates by characterizing the intervening causal mechanism (n1 => n2 => etc.) between the cause(s) (X) and the outcome(s) (Y). The causal mechanism is a chain of events or "empirical manifestations" (nx) linking causes (X) with their long-term effects and eventual outcomes at the end of the study period (Y). It describes "not simply a relationship that has been found, but one that has been found repeatedly." [26]. As such, the more empirical manifestations that are observed within the study period, the more confident researchers can be of the causal mechanism [27]. CPT depends on detailed descriptions of empirical manifestations as well as the concepts linking and/or used to diagnose them, which are based on the overall hypothesis and theories of how X impacts Y. We applied causal process tracing (CPT)—a qualitative, retrospective analytical technique useful for deducing change and causation within a temporal sequence of events [25]. Per Figure 2, CPT operates by characterizing the intervening causal mechanism (n1 => n2 => etc.) between the cause(s) (X) and the outcome(s) (Y). The causal mechanism is a chain of events or "empirical manifestations" (nx) linking causes (X) with their long-term effects and eventual outcomes at the end of the study period (Y). It describes "not simply a relationship that has been found, but one that has been found repeatedly." [26]. As such, the more empirical manifestations that are observed within the study period, the more confident researchers can be of the causal mechanism [27]. CPT depends on detailed descriptions of empirical manifestations as well as the concepts linking and/or used to diagnose them, which are based on the overall hypothesis and theories of how X impacts Y.

**Figure 2.** Elements of the causal process tracing method [27].

At its core, our research is a historical process narrative explaining how GWS governance gaps are likely to have persisted over time to feature in current governance and lead to groundwater insecurity. In this context, CPT was applied to design our analysis as outlined in Table 1.

**Table 1.** Causal process tracing application in research design.


We first characterize the outcomes, providing an overview of GWS governance weaknesses and the emerging problem of groundwater insecurity. In so doing, we describe the human and climate pressures driving GWS vulnerabilities, drawing from official government reports and published literature. We then characterize the emerging GWS decline problem, documenting cases at the sub-watershed scale, using a wide range of indicators including (i) deteriorating water quality with oxygen exposure to lithology [28] and/or upwelling of deeper brines [29]; (ii) collapsing cavities in evaporates (e.g. gypsum) due to dissolution as pumping increases water velocity [30]; (iii) land subsidence due to over-pumping that reduces pore water pressure causing gradual lowering of land [30]; (iv) waning stream levels as baseflow declines [31]; (v) loss of groundwater-dependent ecosystems [32]; (vi) sustained decline of water table levels, defined as the upper limit of the underground where all interstices and voids are saturated with water [33]. Data on these indicators were sourced from desk studies of publicly available reports from peerreviewed journals, GWS monitoring and governance institutions, and responses to our survey distributed from December 2018 to February 2019 to managers in these institutions. We received a 100% response rate.

To deduce the cause and causal mechanism, the evolution of groundwater use policies and environmental safeguards impacting GWS were studied over the introduction of common law principles in the 19th century, up to the adoption of the 2005 Great Lakes–St Lawrence Basin Sustainable Water Resources Agreement (2005 GLSWRA), the most recent binational agreement controlling groundwater use. Economic policies impacting GWS were reviewed up to the 2020 US Mexico Canada Agreement (2020 USMCA). This study period is sufficient as legal concepts foundational to current GWS governance are drawn from 19th century common law (judge-made, case law long applied by appellate courts to resolve legal disputes related to groundwater use and conservation) [34]. From this, multilevel treaties, rules, and statutes (laws made by legislative bodies of governments at multiple levels) have evolved over the years [24]. As policies and standards component to the present-day GWS governance framework have not changed significantly since the 2020 USMCA and 2005 GLSWRA [22], the dates of the adoption of these binational agreements were considered appropriate for delimiting the study period. Data on the historical policies and standards component to the cause and causal mechanism were sourced from peer-reviewed publications, expert interviews, as well as publicly available

government repositories and archives. Policies made by municipalities were not considered as they are not involved in GWS policy and decision making [14,22].

Identification of empirical manifestations and causal linkages was made considering sustainable aquifer yield theory. Aimed at avoiding undesirable social, environmental, and legal outcomes from aquifer pumping, the theory posits a balanced compromise between the contrasting strategies of either little or no pumping of aquifers and the total uptake of natural discharge [8,12,35]. Balancing these opposing governance strategies is largely science-based, as it considers the physical–environmental requirements of aquifers for maintaining GWS [35,36]. We applied the main concepts of sustainable aquifer yield theory as evaluative indicators to identify and assess scopes of policies and standards, pinpointing their changes over the study period, and determining the extent to which they considered (i) the finite volume of groundwater that aquifers can store that is innately limited by their geophysical parameters; (ii) natural recharge of aquifers that are controlled by precipitation and climate; (iii) fluxes required to maintain vital environmental functions; (iv) whether allowed and/or economically incentivized human uses disturbed the equilibrium required to sufficiently maintain GWS while avoiding unwanted outcomes. These evaluations were contextualized by the contemporaneous state of hydrogeological science at key governance milestones, given that the understanding of physical–environmental parameters to maintain GWS evolved over the study period.

To conclude, we synthesized findings, diagnosing the extent to which historical policy gaps have carried over to the current GWS governance framework, and the governance processes by which weaknesses have persisted over time. Insights were then used to link historical governance to emerging GWS decline cases, as well as to provide recommendations to address governance gaps.

#### **3. Results**

*3.1. Outcomes (Y): The Emerging Problem of Groundwater Insecurity and Linked Governance Gaps*

• Characterizing Sub-Watershed-Scale GWS Decline

GLB groundwater is mainly pumped from five principal aquifer systems: the Cambrian– Ordovician, Silurian–Devonian, Mississippian, and Pennsylvanian bedrock aquifers that are composed mainly of carbonates and sandstone, as well as the overlying, surficial aquifer system that is dominated by alluvium and glacial deposits [37]. Due to high permeability and effective porosity, the most productive aquifers are hosted in the unconsolidated sands and gravels of the surficial aquifer system [38] within which most wells are located. As GWS in surficial aquifers is prone to seasonal and climate fluctuations due to their relative shallowness, growing pumping rates often result in long-term groundwater decline, with occurrences being particularly reported in communities located in drought-prone locales and/or are heavily reliant on groundwater [39].

Occurrences of indicators of persistent GWS decline resulting from groundwater overpumping have not yet been comprehensively documented in the GLB [32]. Based on available information, the impacts of over-pumping on GLB stream baseflow and groundwaterdependent ecosystems are poorly understood [13]. However, one well-documented case in Wisconsin linked excessive pumping to the drying of wetlands causing native habitat loss and invasive species spread [40].

Better documented are cases of long-term pumping reducing riverine baseflow given the interconnectedness of the Basin's surface water bodies with groundwater flow systems [41,42]. The Great Lakes are net groundwater receivers, with their tributaries gaining substantial volumes of water fluxes directly from the Basin's groundwater flow systems [42]. Groundwater contributes from 48% of streamflow in the Lake Erie Sub-Basin up to 79% in the Lake Michigan Sub-Basin [43]. Therefore, as over-pumping aquifers can reduce groundwater fluxes to surface water systems, it can diminish stream baseflow or, in extreme cases, reverse the normal flow of groundwater to surface water bodies. One of the most acute examples is occurring in aquifers supplying residents of the Chicago–Milwaukee metropolitan area and the Green Bay, Wisconsin, and Toledo, Ohio area. Here, long-term

pumping has not only reduced stream baseflow but has reversed water flow from surface waters to aquifers [38].

As the Basin's hydrogeologic settings contain a substantial amount of glacial, unconsolidated deposits, some areas are susceptible to land subsidence due to groundwater decline caused by over-pumping [30]. Though not as prevalent in more drought-prone North American states/provinces, localized reports of land subsidence have been reported in Indiana, Wisconsin [44], and Michigan [45]. In regions where aquifers are hosted in karstic rock, sinkholes and cavity collapse can occur due to carbonate dissolution with pumping [46]. To illustrate, municipalities having high risks of gypsum cavity collapse linked to mining dewatering have been documented in Ontonagon, Houghton, Iosco, Keweenaw, Kent, Barry, Eaton, Calhoun, and Jackson counties in Michigan [47].

Upwelling of brines due to excessive mine dewatering has been reported in wells in the townships of Windsor and Romney, Ontario [13]. In Michigan, upwelling of brines due to long-term pumping for drinking water and agriculture has been well documented in Michigan's Lower Peninsula [48], as well as in Ottawa County that abuts northern Lake Michigan [49]. Arsenic concentrations exceeding the US Environmental Protection Agency's maximum contaminant level of 10 µg/L are often reported in well water in Southeast Michigan [50] in the counties of Huron, Tuscola, Sanilac, Lapeer, Genesee, Shiawassee, Livingston, Oakland, Macomb, and Washtenaw. These wells pump the Marshall Sandstone, hosted in the Mississippian basement aquifer system [37]. Relatedly, long-term pumping has caused drinking water of the straddling community of Waukesha, Wisconsin to be contaminated with radium, prompting its successful application for access to GLB water resources [51].

Responses to our survey indicated that persistent groundwater table decline occurs in aquifers supplying roughly 10% of GLB municipalities. Widespread groundwater table decline risks have been modelled in Michigan including the Grand Rapids and the metropolitan area of Detroit and its eight (8) suburban counties including Genesee, Oakland, Macomb, Washtenaw, Wayne, St. Clair, Lapeer, and Monroe (communication from the Department of Environmental Quality on 5 December 2018). This has also been extensively documented in aquifers supplying Milwaukee and Chicago, including its eight (8) eastern suburban counties, as intense pumping beginning in 1864 caused groundwater table levels to decline by as much as 275 m by 1980 [52]. In the Ontario Sub-Basin, aquifers supplying municipalities in the Grand River Watershed, including Kitchener, Waterloo, Cambridge, the City of Guelph, and surrounding townships, have a moderate risk of developing GWS shortages [53]. These risks are particularly in droughts, the summer agricultural growing season, and periods of high municipal water demand used to supply the residential, industrial, and commercial sectors [54].

• Characterizing Present-Day GWS Governance Weaknesses

Incorporated into current federal and state/provincial laws, many of the current policies and decision-making standards governing groundwater use are from the 2005 GLSWRA. The binational agreement, aimed at sustaining the quantity of all GLB waters, generally prohibits withdrawals over 379,000 L/day " . . . in any 30-day period (including Consumptive Uses) from all sources . . . " (defined as bulk water) or diverting any volume of water from the Basin, except when in containers 20 L or less, without a regional review decision-making process by Great Lakes governors/premiers. Parties are urged to promote efficient water use and to record water uses by sector in a regional data base. Water uses below bulk water definitions are considered " . . . reasonable uses . . . " for which GLB states/provinces can set their own regulations. The Great Lakes states passed a series of Great Lakes–St Lawrence Basin Sustainable Resources Compact Acts into law between 2007 and 2008, and Ontario brought these policies into effect in Ontario Regulation 225/14 in 2014. These laws limited the scope of the 2005 GLSWRA regional review process to deciding on large water diversions from the GLB, and gave the states/provinces responsibilities to regulate bulk water use; the most common regulation being Permit to Take Water (PTTW) programs.

Relevant economic policies include the 2020 USMCA, state/provincial PTTW and/or well license fees, and municipal water supply tariffs. As the newest North American free trade treaty, the 2020 USMCA allows export of GLB groundwater when embedded in products. It furthers the scope of past trade agreements, including large, medium, and small enterprises, and removes tariffs on a wider range of agricultural products. It is the only binational agreement impacting GWS with legally binding recourse should enterprises perceive unfair barriers to free trade [55].

With identical policies guiding groundwater and surface water use, with high volumetric water use thresholds for bulk water definitions, binational-to-municipal levels of government often overlook fundamental physical–environmental differences between groundwater and surface water [7]. Sustainable aquifer yield considerations also appear to be largely ignored in federal and state/provincial governance of smaller volumes of GLB groundwater use [56]. Some examples are that policies generally do not include volumetric limits controlling groundwater pumped for agricultural purposes or from smaller-capacity wells on private land for domestic use. Policies guiding aquifer pumping in federal lands are also largely absent [34]. Instead, governmental oversight is typically limited to datarecording requirements and technical specifications for commissioning wells [14].

Economic policy tools generally encourage groundwater overuse, furthering groundwater insecurity risks in vulnerable locations [57]. The 2020 USMCA increases competition for groundwater resources by opening up free trade provisions to a greater pool of enterprises. The removal of trade tariffs on a wider set of agricultural products increases pressure on aquifers given that agriculture is the most intense water-consuming sector within the GLB. At the state/provincial level, higher-capacity wells requiring PTTWs attract low permit fees [14], and groundwater used for agriculture and firefighting are exempt from permits [58]. Finally, graduated block rates of municipal water supply tariffs can incentivize water wastage, as rates become progressively cheaper the more water is used [59].

#### *3.2. Causal Mechanisms: Linking Historical GWS Governance to Current Outcomes*

• Fundamental Legal and Scientific Principles Underpinning the Evolution of GWS Governance In North America, controlling who has access to groundwater has historically been tied to land ownership and property rights [24]. This has its origins in the Absolute Ownership Rule of English common law [60] that allowed landowners to use groundwater below their property without limits or obligations to conserve the resource for neighbors or for future uses [61]. Court deliberations in the earliest documented application of the Absolute Ownership Rule—1843 Chasemore vs. Richards (1843-60 All E.R. 77, 81-82 H.L. 1859)—show that the court did not think it could limit the use of "water percolating through underground strata, which has no certain course and no defined limit, but oozes through the soil in every direction in which the rain penetrates." It is apparent that the Absolute Ownership Rule was originally devised based on the idea that groundwater quantity, flow rates, and flow directions were "unknowable", given the embryonic state of hydrogeological science at the time [62]. Later adopted in early North American governments, the Absolute Ownership Rule was modified to the Reasonable Use Rule, limiting groundwater uses to those done without waste or inhibiting the rights of adjacent property owners to access groundwater within their properties [63].

In multiple levels of GLB government, applying the Reasonable Use Rule to govern groundwater use has been nuanced by the Underground Stream Doctrine and the Public Trust Doctrine. The Underground Stream Doctrine interrelates surface water and groundwater rights of use, resulting in groundwater wells traditionally being treated as surface water diversions and groundwater flow considered "tributary" to GLB surface water [14]. Adding to this is the Public Trust Doctrine that originated from sixth century Roman civil law or "Institutes of Justinian", obliging governments to protect in perpetuity "things common to mankind—the air, running water, the sea, and consequently the shores of the sea." Used as the basis for environmental and natural resource protection

laws, when the Public Trust Doctrine was adopted in the constitutions of newly formed North American states/provinces, governmental responsibilities to protect water resources originally extended only to surface water [63].

In this context, policies, standards, and court decisions governing GLB water use have traditionally prioritized safeguarding surface water quantities. Unless the purpose of groundwater protection has been closely tied to safeguarding surface water quantity for the greater public good, governmental oversight of groundwater use has been lacking, with groundwater use being traditionally treated as a private property rights issue [24]. Remaining largely unchanged over the years, these legal principles have carried through multilevel GWS governance, despite advances in scientific understanding of groundwater's physical–environmental sustainability requirements and its role in providing a range of vital environmental flows beyond baseflow to surface water bodies.
