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Cultural eutrophication—the pollution of water bodies with nutrients such as nitrogen and phosphorus from human activities—and associated harmful algal blooms are key issues facing decision-makers, yet costs are often identified as a barrier to restoration. When designed in collaboration with impacted communities, economic valuation of lake ecosystem services can contribute to informed environmental decision-making by quantifying economic benefits of lake restoration and understanding the trade-offs people are willing to make. Here, we collaborate with the local community, stakeholders, and decision-makers to develop and implement a discrete choice experiment survey to estimate people's preferences and willingness to pay for restoring Elk/Beaver Lake, Canada, which has been experiencing worsening harmful algal blooms and other water quality issues. Over half of survey respondents (66%) indicated that water quality issues impact their use of the lake, and many (52%) indicated they did not feel safe swimming in or allowing their pets to drink from the lake (64%). Responses to the choice experiment are analyzed using choice models which reveal that the annual economic benefits of lake restoration across different model specifications ranged from $141 to $292 CAD per household with substantial heterogeneity across people. The aggregate annual benefits of lake restoration are $27 to $55 million which is notably greater than the estimated costs of restoration plans. This study contributes to the growing literature suggesting that there are substantial benefits to society from restoring lakes, thus the perception of cost as an insurmountable barrier to restoration of bloom-affected lakes requires reconsideration. • Lake degradation and harmful blooms affect community enjoyment of a high-use lake. • Collaboration is useful for informing economic valuation of lake ecosystem services. • Willingness to pay for managing harmful algal blooms and lake restoration is high. • Economic benefits outweigh the costs of lake restoration [ABSTRACT FROM AUTHOR]

The link between under ice processes and open water eutrophication dynamics has been proven in the field. Water quality models still lack the capability to capture the connection between both environments. The hydrodynamic-ecological model CE-QUAL-W2 is being applied to a eutrophic drinking water reservoir on the Canadian Prairies as part of larger collaborative research project. CE-QUAL-W2 is one of the few water quality models that includes an ice algorithm, yet is restricted by a fixed albedo coefficient. Field studies have shown albedo to change through the ice cover season – varying the solar radiation that reaches the ice-water interface as a result. In order to better represent the light and heat environment during the under ice periods we modify the ice algorithm to incorporate a variable albedo rate. While assessing the modified version of CE-QUAL-W2 on the reservoir we encounter a number of challenges during the calibration process. These challenges pertain to difficulties with modelling the under ice environment, and with modelling shallow lakes and reservoirs. We recommend a targeted monitoring program to supplement available data that will reduce the uncertainty associated with the results of the reservoir model. [ABSTRACT FROM AUTHOR]

Abstract: Freshwater lakes are known to release carbon dioxide (CO2) and methane (CH4) to the atmosphere; however, the importance of lakes in global nitrous oxide (N2O) budgets is not yet known. Further, despite the abundance of small lakes on the landscape, neither emissions of these gases nor their drivers are well described. Dissolved concentrations of CO2, CH4 and N2O greenhouse gases were related to water chemistry, hydrology and catchment characteristics in order to identify factors controlling gas concentrations for 121 small Irish headwater lakes (median area: 2.0ha) in relatively undisturbed catchments; lake–atmosphere gas fluxes were also calculated. The majority of lakes were supersaturated (relative to the atmosphere) with CO2 and N2O while CH4 was above saturation in all lakes. Dissolved gas concentrations were correlated with land cover (rock, forest and grassland), deuterium excess (an indicator of hydrologic character) and lake organic carbon concentrations, although dissolved CO2 exhibited few significant relationships. Principal components analysis indicated that higher levels of CH4 and N2O supersaturation were exhibited under different conditions. Methane supersaturation was highest in low elevation catchments with an evaporative hydrologic character and high organic carbon concentrations. In contrast, lakes characteristic of N2O supersaturation were low in carbon and located in more rapidly flushed higher elevation catchments. Estimated fluxes of CO2, CH4 and N2O to the atmosphere averaged 14, 0.36 and 1.3×10−3 mmolm−2 d−1, respectively. [Copyright &y& Elsevier]

Abstract The heterogeneity of dissolved organic matter (DOM) in natural and human impacted waters and the variety of drinking water treatment processes employed has made a mechanistic understanding of disinfection byproduct (DBP) formation challenging. In this study, we examined the formation of the regulated DBPs (Trichloromethanes, THM, and Haloacetic acids, HAA) during full-scale water treatment operations both with prechlorination treatment (normal operations for the drinking water plant) and without (altered operations); followed by coagulation, flocculation, filtration, and chlorination. The source water DOM concentration ranged 6.4 to 7.3 mg-C/L. DOM composition was moderately humic and degraded with a mix of microbial- and terrestrial-like characteristics. Removal of raw water prechlorination caused an average reduction in total THM and HAA concentrations of 52.7% and 40.0%, respectively, with the greater reduction noted for chlorinated-DBPs rather than brominated-DBPs. Prechlorination treatment resulted in a higher relative production of Cl 3 CH and BrCl 2 CH associated with aromatic, humic, and terrestrial-like DOM. Without prechlorination, the DBP pool had higher proportions of brominated-DBPs (Br 3 CH, Br 2 ClCH, Br 2 CHCOOH, BrClCHCOOH, and BrCH 2 COOH) associated with microbial-like, processed humic-like, and protein-like DOM. These observed patterns could not be explained by chloride demand and DOM concentration, indicating that DOM composition played an important role in DBP formation. Graphical abstract Unlabelled Image Highlights • Changing surface water quality can alter disinfection byproduct (DBP) formation. • A plant-scale change was performed to measure effects of removing prechlorination. • Operational changes altered organic matter quality and DBP type and amount. • Removal of prechlorination was only effective in reducing a subset of DBPs. • Br-containing DBPs were less impacted by operationally change than Cl-DBPs. [ABSTRACT FROM AUTHOR]

Algal blooms fueled by phosphorus (P) enrichment are threatening surface water quality around the world. Although P loss from arable land is a critical contributor to P loads in many agricultural watersheds, there has been a lack of understanding of P loss patterns and drivers across regions. Here, we synthesized edge-of-field P and sediment runoff data for 30 arable fields in the Canadian provinces of Saskatchewan, Manitoba and Ontario (a total of 216 site-years) to elucidate spatial and temporal differences in runoff and P mobilization in snowmelt and rainfall runoff, and discuss climatic, soil and management drivers for these patterns. Across all regions, precipitation inputs were positively correlated with runoff amounts and consequently P loads. Runoff and P losses were dominated by snowmelt across all sites, however, regional differences in runoff amounts, and P concentrations, loads and speciation were apparent. Proportions of total P in the dissolved form were greater in the prairie region (55–94% in Manitoba) than in the Great Lakes region (26–35% in Ontario). In Manitoba, dissolved P concentrations in both snowmelt and rainfall runoff were strongly positively correlated to soil Olsen P concentrations in the 0–5 cm soil depth; however, this relationship was not found for Ontario fields, where tile drainage dominated hydrologic losses. Although precipitation amounts and runoff volumes were greater in Ontario than Manitoba, some of the greatest P loads were observed from Manitoba fields, driven by management practices. This synthesis highlights the differences across the Canadian agricultural regions in P runoff patterns and drivers, and suggests the need of co-ordinated and standardized monitoring programs to better understand regional differences and inform management. Phosphorus runoff patterns vary with climatic regions across Canada. †The dissolved P was measured as total dissolved P in MB and dissolved reactive P in SK and ON. ‡Total P was not measured in SK. [Display omitted] • Phosphorus runoff patterns and drivers vary with climatic regions across Canada. • Co-ordinated and standardized monitoring programs are key to clarify regional differences. • Snowmelt dominates runoff volume and phosphorus loss across Canada. • The predominant form of P in runoff differs between the Prairie region and the Great Lakes region. • Reducing phosphorus sources is important for mitigating phosphorus runoff. [ABSTRACT FROM AUTHOR]

The distribution and quality of water resources vary dramatically across Canada, and human impacts such as land-use and climate changes are exacerbating uncertainties in water supply and security. At the national level, Canada has no enforceable standards for safe drinking water and no comprehensive water-monitoring program to provide detailed, timely reporting on the state of water resources. To provide Canada's first national assessment of lake health, the NSERC Canadian Lake Pulse Network was launched in 2016 as an academic-government research partnership. LakePulse uses traditional approaches for limnological monitoring as well as state-of-the-art methods in the fields of genomics, emerging contaminants, greenhouse gases, invasive pathogens, paleolimnology, spatial modelling, statistical analysis, and remote sensing. A coordinated sampling program of about 680 lakes together with historical archives and a geomatics analysis of over 80,000 lake watersheds are used to examine the extent to which lakes are being altered now and in the future, and how this impacts aquatic ecosystem services of societal importance. Herein we review the network context, objectives and methods. Unlabelled Image • About 90% of Canada's municipal drinking water supplies are from surface waters. • An academic-government group is providing the first national review of lake health. • Over 100 variables were sampled at about 680 lakes across Canada. • Topics range from greenhouse gases to emerging contaminants to invasive pathogens. • The impacts of land-use and climate changes on lake health are also studied. [ABSTRACT FROM AUTHOR]