The Great Lakes Region and Bulk Water Exports

Abstract

The article provides an overview of the latest developments in the debate concerning the bulk water export of Great Lakes water. It examines the policy and legal dimensions of this new debate. The policy dimension focuses on the public attention and concern, in Canada, regarding bulk water removals from the Great Lakes basin. This concern has triggered the new Canadian federal legislation banning water exports from the region (Bill C-15). Is this a sign that the Canadian government now embraces a water conservation ethic? Is its position in line with the recent recommendations on the issue of the International Joint Commission (IJC), the joint body created by the United States and Canada to manage its shared waters? The attempt by investors to export water from the Great Lakes basin raises issues regarding Canada's obligations under international and regional trade agreements, most notably the General Agreement on Tariffs and Trade (GATT) and the North American Free Trade Agreement (NAFTA). The article examines the provisions of those two trade agreements in the context of the water export debate in Canada and concludes that increased clarity on Canada/US transboundary water issues is required.     

Dividing the waters: The case for hydrologic separation of the North American Great Lakes and Mississippi River Basins

Legislation has been introduced this year in the U.S. Congress, but not yet enacted, that would direct the U.S. Army Corps of Engineers to complete a study of the options that would prevent the spread of aquatic nuisance species between the Great Lakes and Mississippi River Basins. Hydrologic separation is the only option which closes the aquatic connection between the two basins and does not require continuous operation and maintenance of various technologies that have some risk of failure. The one-time, capital cost to separate the two basins is widely acknowledged to be high, and the outstanding question is whether the costs are justified given the significant risk of future ecological damages and long-term economic losses. Interests opposing separation have mounted a public campaign that the news media have picked up to deny that hydrologic separation should be considered or that a problem even exists. The campaign rests on four assertions: (1) existing electric barriers in the Chicago canals are effective; (2) it is too late--the carps are already in the Great Lakes or soon will be; (3) Asian carps will not thrive in the Great Lakes due to inadequate food and spawning habitat; and (4) Asian carps are unlikely to cause serious harm. Our review of these assertions and the ecological and socio-economic threats to both basins supports our recommendation that the pending legislation be passed and that it include analysis of hydrologic separation of the two basins.     

Revisiting the Great Lakes Water Quality Agreement phosphorus targets and predicting the trophic status of Lake Michigan

LM3-Eutro is a high-resolution eutrophication model with several improved features lacking in historical Great Lakes models. We calibrated LM3-Eutro using a 2-year (1994-1995) dataset and performed a hindcast simulation from 1976 to 1995 to evaluate the model's ability to make predictions over an extended period of time. Results show a reasonable agreement between model output and field data over this time period. The model predicted that an annual loading of 5600 metric tons (MT) would result in a lake-wide annual total phosphorus (TP) concentration of 7.5 μg L^− 1. Using best estimates of future TP loadings, LM3-Eutro forecasts suggest that Lake Michigan will remain oligotrophic and will continue to meet the 7 μg L^− 1 spring TP concentration Great Lakes Water Quality Agreement objective.     

Automated Mapping of Surface Water Temperature in the Great Lakes

A procedure for producing daily cloud-free maps of surface water temperature in the Great Lakes has been developed. It is based on satellite-derived AVHRR (Advanced Very High Resolution Radiometer) imagery from NOAA's CoastWatch program. The maps have a nominal resolution of 2.6 km and provide as complete as possible coverage of the Great Lakes on a daily basis by using previous imagery to estimate temperatures in cloud covered areas. Surface water temperature estimates derived from this procedure compare well with water temperatures measured at the eight NOAA weather buoys in the lakes. The mean difference between the buoy temperature and the satellite-derived temperature estimates is less than 0.5°C for all buoys. The root mean square differences range from 1.10 to 1.76°C.As one example of the possible applications of this product, the daily surface water temperature maps for 1992 to 1997 were analyzed to produce daily estimates of average surface water temperature for each lake. Results are compared to the long-term (28 year) mean annual cycle of average surface water temperatures. The average surface water temperatures vary from as much as 4°C below climatology in 1993 to 2 to 3°C above climatology in 1995. The new analysis procedure also provides a more realistic depiction of the spatial distribution of temperature in the springtime than the climatological maps.     

A tale of two Great Lakes conferences: Urging global collaboration on our largest freshwater resources

Scientific meetings and conferences are a part of the scientific process, and can facilitate collaboration, idea-sharing, and harmonization of research and management. The success of a conference can be measured using many criteria, including consistency and reoccurrence of the meetings, credibility by participation of reputable professionals, and attendance by a diverse community. In the interest of increasing the success of large-lake, freshwater science, policy, and management, this comment focuses on two recent conferences attended by the authors: the 60th annual meeting of the International Association for Great Lakes Research, in Detroit, U.S.A., and the African Great Lakes Conference, in Entebbe, Uganda. By our measures of success, we suggest that to make a larger impact on research, policy, and management of global, large, freshwater lakes that each conference can improve, either through greater diversity of experts from the global freshwater research community, or by consistently reoccurring on a regular basis.     

Impacts of climate change on groundwater in the Great Lakes Basin: A review

Climate change has the potential to alter the physical and chemical properties of water in the Great Lakes Basin, in turn impacting ecological function. This study synthesizes existing research associated with the potential effects of a changing climate on the quality and quantity of groundwater in the Great Lakes Basin. It includes analyses of impacts on (1) recharge, (2) groundwater storage, (3) discharge and groundwater-surface water (GW-SW) interactions, (4) exacerbating future urban development impacts on groundwater, (5) groundwater quality, and (6) ecohydrology.Large spatial and temporal (i.e., seasonal) variability in groundwater response to climate change between regions is anticipated. Most studies combine field observations with modelling, but many have focused only on small/medium basins. At these small scales, groundwater systems are generally projected to be fairly resilient to climate change impacts. However, modelling studies of larger basins (e.g., Grand River, Saginaw Bay, Maumee River) predict an increase in groundwater storage. Uncertainty in model simulations, particularly from climate models that are used to force hydrological models, is a major challenge. There have been too few studies to date that investigate the interplay of climate change and groundwater quality in the Great Lakes Basin to draw conclusions about future groundwater quality and ecohydrology.A summary of methods, models, and technology is provided. Model uncertainty has become an increasingly important topic and is also discussed. The study concludes with a synthesis of the main science needs to understand groundwater impacts in order to adapt to a changing climate in the Great Lakes Basin.     

Inter‐habitat variation in the benthos of the Upper Missouri River (North Dakota,USA): implications for Great River bioassessment

We examined inter‐habitat variation in benthic macroinvertebrate assemblages in the 180‐km Garrison Reach of the Upper Missouri River, North Dakota (USA) in 2001–2003. The Garrison Reach is unchannelized with a mostly rural setting. Flows are regulated by Garrison Dam. We sampled benthos from three habitats defined a priori: channel, shoreline, and backwater. Benthic assemblages were different in each habitat. Average Bray‐Curtis dissimilarity in assemblage composition ranged from 89% for backwater versus channel habitat to 70% for backwater versus shoreline habitat. There were distinct intra‐habitat groups within a priori habitats: channel assemblages included moving‐sand assemblages and other‐substrate channel assemblages; backwater assemblages included connected (to the river channel) and unconnected backwater assemblages; shorelines assemblages varied between natural (unprotected) and riprap (rock revetment) shorelines. Abundance and taxa richness were lowest and spatial variability highest for moving‐sand channel assemblages. Abundance was highest in backwaters. Taxa richness in backwaters and along channel shorelines were similar. Assemblages in all three habitats were dominated by Nematoda, Oligochaeta and Chironomidae. Taxa in these groups comprised at least 80% of mean abundance in all three habitats. Taxa that discriminated among habitats included the psammophilic chironomid Chernovskiia for moving‐sand channel substrates versus all other habitats; Hydroptila (Trichoptera) for riprap vs natural shorelines, Aulodrilus (Oligochaeta) for connected versus unconnected backwaters; and Nematoda for backwater versus channel and shoreline versus channel. Based on overlap patterns in benthic assemblages among habitats, we concluded that sampling main channel shorelines should also capture much of the natural and stressor‐induced variation in connected backwater and channel habitat exclusive of moving‐sand channel habitat. Published in 2006 by John Wiley & Sons, Ltd.     

Trends in Water Clarity of the Lower Great Lakes from Remotely Sensed Aquatic Color

Satellite observations of aquatic colour enable environmental monitoring of the Great Lakes at spatial and temporal scales not obtainable through ground-based monitoring. By merging data from the Coastal Zone Color Scanner (CZCS) and the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), monthly binned images of water-leaving radiance over the Great Lakes have been produced for the periods 1979–1985 and 1998–2006. This time-series can be interpreted in terms of changes in water clarity, showing seasonal and inter-annual variability of bright-water episodes such as phytoplankton blooms, re-suspension of bottom sediments, and whiting events. Variations in Secchi disk depth over Lakes Erie and Ontario are predicted using empirical relationships from coincident measurements of water transparency and remotely-sensed water-leaving radiance. Satellite observations document the extent to which the water clarity of the lower Great Lakes has changed over the last three decades in response to significant events including the invasion of zebra mussels. Results confirm dramatic reductions in Lake Ontario turbidity in the years following mussel colonization, with a doubling of estimated Secchi depths. Evidence confirms a reduction in the frequency/intensity of whiting events in agreement with suggestions of the role of calcium uptake by mussels on lake water clarity. Increased spring-time water clarity in the eastern basin of Lake Erie also corroborates previous observations in the region. Despite historical reports of localised increases in transparency in the western basin immediately following the mussel invasion, image analysis shows a significant increase in turbidity between the two study periods, in agreement with more recent reports of longer term trends in water clarity. Through its capacity to provide regular and readily interpretable synoptic views of regions undergoing significant environmental change, this work illustrates the value of remotely sensing water colour to water clarity monitoring in the lower Great Lakes.     

Trace element loads in the Great Lakes Basin: A reconnaissance

Water quality data for trace elements in the Great Lakes are relatively scarce, complicating the assessment of current trace element baselines and their distribution patterns. Here, we present concentration data for >40 major and trace elements in >100 samples from the Great Lakes connecting channels, surface waters, precipitation and select Canadian tributaries, to establish a high-level assessment of loading rates across the basin. Contrasting upstream-to-downstream trends were observed for the investigated trace elements, ranging from net-decreasing (>5-fold for e.g., Co, Tl, Y) to net-increasing surface water concentrations (>2-fold for e.g., Sb, U, As). Calculated loading rates reveal different, element-specific controls of runoff, connecting channel loads or precipitation on trace element occurrence. Lake-wide elemental mass-balances could be reasonably closed for conservative trace elements (e.g., Li, <53% residual) but not for others (e.g., rare earth elements with up to 5-fold discrepancies), reflective of general data scarcity and uncertainty in loading rates. In line with major water quality trends, spatial distribution patterns in Lakes Erie and Ontario display subtle near-shore to off-shore heterogeneity for a few trace elements (<1 order-of-magnitude for V or Se), but higher variability for trace elements with significant inputs derived from tributaries. This work provides important quantitative baseline data for trace elements in the Great Lakes that may help optimize surveillance and management strategies for the preservation of Great Lakes water quality.     

Effects of Great Lakes Water Loading upon Glacial Isostatic Adjustment and Lake History

Over the last century geological studies of the ancestral Great Lakes have confirmed that the large surface load of the Laurentide ice sheet deformed the region causing tilting of ancient lake shorelines. Models of this glacial isostatic adjustment mechanism have promoted understanding of this process but have only included ice sheet loads as the source of earth deformation in the region. We describe a method, utilizing a model of glacial isostatic adjustment combined with GIS, that recreates the paleohydrology of the Great Lakes. Predictions include the extent of late glacial, postglacial, and Holocene lakes and their associated outlets and bathymetries. This predicted history of the Great Lakes is similar to that obtained from a century of detailed field studies but our method uses only the present digital elevation model, a prescribed ice sheet chronology, and an assumed earth viscoelastic rheology. Ancient lake bathymetry predictions provide an estimate of water loads associated with each lake. The effect of these lake loads upon vertical deformation of the Great Lakes region is shown to be small, less than 15 m, but not insignificant when compared to approximately 150 m of deformation forced by ice and ocean loads. Maximum lake-induced deformation is centered upon Lake Superior where water depths were greatest. Where topography is low relief, prediction of shoreline locations should include the lake loading effect as well as the ice and ocean loads.     

Opportunities for bipartisanship: Comparing water and energy policy in the Great Lakes region

The Great Lakes contain most of the United States’ surface freshwater and provide deep personal and economic connections for the residents of the region. These connections create an opportunity for bipartisanship in environmental policies with the potential to permeate energy policies. To explore that possibility, this paper examines how party affiliation affects support for water policy and energy policy in the Great Lakes region of the United States. Data from the Great Lakes Region Public Opinion Survey asked 696 Republicans, Independents, and Democrats from the Great Lakes region to respond to a range of environmental policy prompts. Responses to the policy prompts are grouped into four components: Water Quality, Water Diversions, Traditional Fuels, and Renewables. The results find that there is bipartisan support for the Water Quality and Water Diversions components. Energy policies do not receive the same bipartisan support, with Democrats and Independents having more support for the Renewables component while Republicans have more support for the Traditional Fuels component. However, when the fuel source is tied to its pollutants of the Great Lakes, then reactions to that fuel source receive a bipartisan response. The results of this research suggest that embedding water policy in energy policy may allow those policies to receive more bipartisan support. Combining water policy and energy policy can depolarize some of the politics surrounding environmental policy broadly.     

Alkalinity,pH, and pCO2 in the Laurentian Great Lakes: An initial view of seasonal and inter-annual trends

Ongoing human perturbations to the global inorganic carbon cycle can cause various changes in the pH and alkalinity of aquatic systems. Here seasonal and inter-annual trends in these variables were investigated in the five Laurentian Great Lakes using data from the U.S. EPA GLENDA database. These observations, along with temperature, were also used to predict the partial pressure of carbon dioxide in surface water (pCO₂). There are strong seasonal differences in pH in all five lakes, with higher pH levels in summer than in spring. All lakes show significantly higher pCO₂ values in spring than in summer. Michigan and Ontario show higher alkalinity values in spring; Huron shows lower spring values. Inter-annually, open-lake pH shows the highest values in all lakes around 2010, the time frame of lowest lake water levels, though only lakes Superior and Erie show statistically significant inflection points at that time. Inter-annual alkalinity trends differ considerably from those of pH. Superior’s alkalinity increases until ～2008 and then begins dropping; Ontario’s alkalinity decreases until ～2004 and then begins increasing, with the decrease coinciding with the introduction and establishment of Dreissenid mussels. The other lakes show much less clear inter-annual alkalinity trends. For pCO₂, inter-annual trends in each lake show either increases from 1992 to 2019 (for Superior, Michigan, and Huron) or shifts from slightly decreasing values to increasing values for the other lakes. The timing of this shift is from 2008 to 2010.     

Influence of lake levels on water extent,interspersion, and marsh birds in Great Lakes coastal wetlands

Coastal wetlands in the Laurentian Great Lakes undergo frequent, sometimes dramatic, physical changes at varying spatial and temporal scales. Changes in lake levels and the juxtaposition of vegetation and open water greatly influence biota that use coastal wetlands. Several regional studies have shown that changes in vegetation and lake levels lead to predictable changes in the composition of coastal wetland bird communities. We report new findings of wetland bird community changes at a broader scale, covering the entire Great Lakes basin. Our results indicate that water extent and interspersion increased in coastal wetlands across the Great Lakes between low (2013) and high (2018) lake-level years, although variation in the magnitude of change occurred within and among lakes. Increases in water extent and interspersion resulted in a general increase in marsh-obligate and marsh-facultative bird species richness. Species like American bittern (Botaurus lentiginosus), common gallinule (Gallinula galeata), American coot (Fulica americana), sora (Porzana carolina), Virginia rail (Rallus limicola), and pied-billed grebe (Podilymbus podiceps) were significantly more abundant during high water years. Lakes Huron and Michigan showed the greatest increase in water extent and interspersion among the five Great Lakes while Lake Michigan showed the greatest increase in marsh-obligate bird species richness. These results reinforce the idea that effective management, restoration, and assessment of wetlands must account for fluctuations in lake levels. Although high lake levels generally provide the most favorable conditions for wetland bird species, variation in lake levels and bird species assemblages create ecosystems that are both spatially and temporally dynamic.     

对引江济太调水试验工程的初步认识和探讨

引江济太调水试验工程自2002年实施以来,取得了显著的经济效益和社会效益,是太湖流域实施由汛期调度向全年调度,由水量调度向水资源综合调度的有益尝试.通过对引江济太作用和效果的分析,阐述了在流域综合治理的总体框架下,统筹协调各方面关系,解决经济社会发展和水生态环境之间的突出矛盾和问题,强调要以流域水资源配置和改善流域水生态环境为重点.加强工程和非工程设施建设和运行管理,实现洪涝相机调度,探索和实践流域管理的新策略.     

A pound of prevention,plus a pound of cure: Early detection and eradication of invasive species in the Laurentian Great Lakes

Ballast water regulations implemented in the early 1990s appear not to have slowed the rate of new aquatic invasive species (AIS) establishment in the Great Lakes. With more invasive species on the horizon, we examine the question of whether eradication of AIS is a viable management strategy for the Laurentian Great Lakes, and what a coordinated AIS early detection and eradication program would entail. In-lake monitoring would be conducted to assess the effectiveness of regulations aimed at stopping new AIS, and to maximize the likelihood of early detection of new invaders. Monitoring would be focused on detecting the most probable invaders, the most invasion-prone habitats, and the species most conducive to eradication. When a new non-native species is discovered, an eradication assessment would be conducted and used to guide the management response. In light of high uncertainty, management decisions must be robust to a range of impact and control scenarios. Though prevention should continue to be the cornerstone of management efforts, we believe that a coordinated early detection and eradication program is warranted if the Great Lakes management community and stakeholders are serious about reducing undesired impacts stemming from new AIS in the Great Lakes. Development of such a program is an opportunity for the Laurentian Great Lakes resource management community to demonstrate global leadership in invasive species management.     

Morphometric differentiation and gene flow in emerald shiners (Notropis atherinoides) from the lower Great Lakes and the Niagara River

Differences in habitat (e.g., water velocity, prey, and predator regimes) are a driving force causing adaptive divergence among fish populations. This study used geometric shape analysis to assess morphological differences among emerald shiner (Notropis atherinoides) populations inhabiting the Niagara River, Lake Erie, and Lake Ontario. It was expected that emerald shiners inhabiting the two lakes would have more robust bodies and smaller heads, while river emerald shiners were expected to display more fusiform bodies with larger heads. The results of this study indicate that emerald shiners from Lake Erie and the Niagara River had a more robust form on average than individuals from Lake Ontario. Specifically, emerald shiners collected from Lake Ontario displayed more streamlined bodies and larger heads than emerald shiners collected from Lake Erie and the Niagara River. In addition, this divergence in body shape has apparently occurred despite the lack of distinct genetic differentiation as measured with microsatellite variation. Our results suggest that differences in water velocity alone may not be responsible for phenotypic variation in body shape among these emerald shiner populations, and other factors such as differences in prey or predator regimes are likely involved.     

南水北调与黄河未来水量分配

未来南水北调工程的实施,将会置换出一部分黄河水量,这部分水量在流域上中游的再分配将会对整个黄河流域水资源的合理开发利用产生极为深刻的影响。根据黄河流域上中游各省（区）实际情况,在保证经济社会用水和必要的生态环境用水的前提下,运用层次分析和模糊决策理论相结合的方法,对南水北调东线、中线和西线工程不同水平年、不同调水规模情况下,黄河可置换水量在流域上中游的再分配问题进行了探讨。     

Dominant glacial landforms of the lower Great Lakes region exhibit different soil phosphorus chemistry and potential risk for phosphorus loss

Phosphorus (P) losses from agricultural soils are a growing economic and water-quality concern in the Lake Erie watershed. While recent studies have explored edge-of-field and watershed P losses related to land-use and agricultural management, the potential for soils developed from contrasting parent materials to retain or release P to runoff has not been examined. A field-based study comparing eight agricultural fields in contrasting glacial landscapes (hummocky coarse-textured till-plain, lacustrine and fine-textured till-plain) showed distinct physical and geochemical soil properties influencing inorganic P (P_i) partitioning throughout the soil profile between the two regions. Fields located on the coarse-textured till-plain in mid-western Ontario, Canada had alkaline calcareous soils with the highest Total-P_i concentrations and the majority of soil P_i stored in an acid-soluble pool (up to 91%). In contrast, loosely to moderately soluble P_i concentrations were higher in soils of the lacustrine and fine-textured till-plain in southwestern Ontario, northeast Indiana and northwestern Ohio, US. Overall, soils on the lacustrine and fine-textured till-plain had a greater shrink swell-capacity, likely creating preferential flow to minimize P_i interaction with the more acidic, lower carbonate and lower sorption capacity soils. These differences in soil P_i retention and transport pathways demonstrate that in addition to management, the natural landscape may exert a significant control on how P_i is mobilized throughout the Lake Erie watershed. Further, results indicate that careful consideration of region-specific hydrology and soil biogeochemistry may be required when designing appropriate management strategies to minimize P_i losses across the lower Great Lakes region.     

Dissolved Organic Matter in the Great Lakes: Role and Nature of Allochthonous Material

Dissolved organic matter (DOM) quality and the modifying influence of light on DOM bioavailability were investigated along a natural gradient of allochthonous influence in the lower Great Lakes. Using parallel factor analysis (PARAFAC), three DOM fluorophores were identified. One fluorophore, previously identified as peak C, was of allochthonous (component 1) origin and two previously uncharacterized fluorophores were identified as autochthonous (components 2 and 3). Component 1 was photoreactive and the dominant form in creek water samples while components 2 and 3 were dominant in Hamilton Harbour and lake water samples. Components 2 and 3 showed limited photoreactivity. Exposure to full spectrum irradiance decreased the average molecular weight of DOM (i.e., increased the absorbance ratio (a254:a365)) for all water samples. DOM bioavailability was lowest in creek and highest in lake water samples and was inversely related to DOM average molecular weight. Photomodification of DOM resulted in higher bacterial activity although these differences were not significantly different. This suggests that light plays a significant role in the cycling of terrestrially-derived DOM and to a certain extent autochthonous DOM, potentially increasing metabolism of both terrestrially and microbially derived DOM in the Great Lakes aquatic ecosystems.