The data consists of temperature indices based on homogenized daily maximum and minimum temperatures at 338 locations across Canada, and of precipitation indices based on adjusted daily rainfall, daily snowfall and daily precipitation amounts at 463 locations across the country. These indices were selected for their relevance to social and economic impact assessment in Canada and for the insights they could provide regarding changes in extreme climate conditions. Please refer to the papers below for detailed information regarding the adjustment procedures and the trends in the indices.

This dataset provides geospatial polygon boundaries for marine bivalve shellfish harvest area classification in Canada (British Columbia, New Brunswick, Newfoundland and Labrador, Nova Scotia, Prince Edward Island and Quebec). These data represent the five classification categories of marine bivalve shellfish harvest areas (Approved; Conditionally Approved; Restricted; Conditionally Restricted; and Prohibited) under the Canadian Shellfish Sanitation Program (CSSP). Data are collected by Environment and Climate Change Canada (ECCC) for the purpose of making applicable classification recommendations on the basis of sanitary and water quality survey results. ECCC recommendations are reviewed and adopted by Regional Interdepartmental Shellfish Committees prior to regulatory implementation by Fisheries and Oceans Canada (DFO). These geographic data are for illustrative purposes only; they show shellfish harvest area classifications when in Open Status. The classification may be superseded at any time by regulatory orders issued by DFO, which place areas in Closed Status, due to conditions such as sewage overflows or elevated biotoxin levels. For further information about the current status and boundary coordinates for areas under Prohibition Order, please contact your local DFO office.

Patterns of wet deposition of the nitrate (NO3), non-sea-salt sulfate (xSO4) and ammonium (NH4) ions across areas of Canada and the United States are based on measurements of precipitation depth and ion concentrations in precipitation samples. xSO4 refers to the wet deposition of sulfate with the sea-salt sulfate contribution removed at coastal sites. These measurements were collected and quality controlled by their respective networks: in Canada, the federal Canadian Air and Precipitation Monitoring Network (CAPMoN) and provincial or territorial networks in Alberta, New Brunswick, the Northwest Territories, Nova Scotia, Ontario and Quebec. In the United States, wet deposition measurements were made by two coordinated networks: the National Atmospheric Deposition Program (NADP) / National Trends Network (NTN) and the NADP/Atmospheric Integrated Research Monitoring Network (AIRMoN). Total annual deposition from each site was screened for completeness using the following criteria: (1) precipitation amounts were recorded for >90% of the year and >60% of each quarter, and (2) a nitrate/sulfate/ammonium concentration was reported for >70% of the precipitation measured over the year and for >60% of each quarter. Only data from sites that were designated as regionally representative were used in the mapping. Annual deposition amounts were interpolated by ordinary kriging using ArcMap Geostatistical Analyst. The map is limited to the contiguous U.S. and southeastern or southern Canada because outside that region, the interpolation error exceeds 30% due to the larger distances between stations. The units for annual wet deposition fluxes are in kg of NO3, SO4 or NH4 per hectare (kg ha-1). Wet deposition maps are available as geodatabase files (*.gdb) compatible with geospatial software (e.g. ESRI ArcGIS) and as a KMZ file compatible with virtual globe software (e.g. Google Earth™). Maps can also be viewed online via Open Maps and the ArcGIS online viewer.

The Wastewater Systems Effluent Regulations (WSER), developed under the Fisheries Act, came into force in 2012 to manage wastewater releases by systems that collect an average daily influent volume of 100 cubic metres or more. The WSER also does not apply to any wastewater system located in the Northwest Territories, Nunavut and north of the 54th parallel in the provinces of Quebec and Newfoundland and Labrador. The WSER set national baseline effluent quality standards that are achievable through secondary wastewater treatment. The regulations also specify requirements for carrying out effluent monitoring, reporting and record keeping. These files contain information about each wastewater system as reported in the Effluent Regulatory Reporting Information System (ERRIS) by the owners/operators of each wastewater system subject to the WSER for the years 2013 to 2021. The datasets include wastewater system information such as treatment types and discharge point locations, concentrations of carbonaceous biochemical oxygen demanding matter and suspended solids, acute lethality test results, and volumes of effluent discharged from the final discharge point and from combined sewer overflow points. The WSER dataset includes map layers that can be accessed from the Open Maps website or they can be linked to a geographic information system (GIS). Data from Quebec and Yukon The data for Quebec municipalities (after 2017) is provided to the department separately through the equivalency agreement that was finalized in October 2018. Combined sewer overflow volumes and acute lethality results are not included for Quebec municipalities as it is not included in the data provided under the equivalency agreement. Beginning in 2015, the data reported for the Yukon is provided to the department separately through an equivalency agreement finalized in 2014. Acute lethality results are not included as part of the data provided by the Yukon under the equivalency agreement. Supplemental Information Environment and Climate Change Canada (ECCC) developed the Effluent Regulatory Reporting Information System for the owners of wastewater systems subject to the WSER to submit identification reports, on-going effluent monitoring reports, combined sewer overflow reports as well as transitional and temporary authorization applications. The reports are submitted to ECCC to assess compliance with the national effluent quality standards for carbonaceous biochemical oxygen demanding matter and suspended solids. Certain regulatees are also required to submit the results of acute lethality testing. More information on the wastewater sector including the regulations, agreements, contacts and resource documents is available at: https://www.canada.ca/wastewater Additional information and data on federal infrastructure funding for wastewater is available through Infrastructure Canada - see link “Infrastructure Canada Projects” in Data and Resources below.

The Canadian Environmental Sustainability Indicators (CESI) program provides data and information to track Canada's performance on key environmental sustainability issues. The Water quality in Canadian rivers indicators provide a measure of the ability of river water across Canada to support plants and animals. At each monitoring site, water quality data are compared to water quality guidelines to create a rating for the site. If measured water quality is below the guidelines, it can maintain a healthy ecosystem. Water quality at a monitoring site is considered excellent when parameters in a river very rarely exceed their guidelines. Conversely, water quality is rated poor when parameters usually exceed their guidelines, sometimes by a wide margin. These indicators provide information about the state of surface water quality and its change through time, to support water resource management. Information is provided to Canadians in a number of formats including: static and interactive maps, charts and graphs, HTML and CSV data tables and downloadable reports. See the supplementary documentation for the data sources and details on how the data were collected and how the indicator was calculated.

HREPA is part of the NSRPS (National Surface and River Prediction System) experimental system dependent on two other systems. It uses surface station observations and radar QPEs pre-processed by HRDPA and disturbed trial fields generated by the Canadian Land Data Assimilation System (CaLDAS). HREPA produces four precipitation analyses per day on 6-hour accumulations valid at synoptic times (00, 06, 12, and 18 UTC). Each analysis set contains 24 members plus the control member. A quality index (confidence index) is also available on the same grid as the precipitation fields. Finally, two percentiles, 25th and 75th, estimated on these sets are also provided for each synoptic hour. Currently, there is only a high-resolution version of the system, whose domain covers Canada and the northern United States with a horizontal resolution of about 2.5km.

The Regional Ensemble storm Surge Prediction System (RESPS) produces storm surge forecasts using the DalCoast ocean model. DalCoast (Bernier and Thompson 2015) is a storm surge forecast system for the east coast of Canada based on the depth-integrated, barotropic and linearized form of the Princeton Ocean Model. The model is forced by the 10 meters winds and sea level pressure from the Global Ensemble Prediction System (GEPS).

Lake Winnipeg, located in Manitoba, is approximately 25,000 square kilometers and is the tenth largest freshwater lake in the world. The mean depth is approximately 12 m. Lake Winnipeg's water shed encompasses 4 provinces, 4 states and over 100 Indigenous Nations. Economic benefits include a $110 million tourism and recreation industry and a $25 million commercial and sport fishing industry. In recent years, excessive nutrients have led to increases in frequency and severity of cyanobacteria blooms. Phase I of the Lake Winnipeg Basin Initiative (LWBI) (2008-2012) was implemented to determine scientific gaps pertaining to sources and transport mechanisms for nutrients and asses ecology and nutrient cycling. Phase II (2012-2017) encompasses monitoring and further research on priority gaps and to measure results and effectiveness of cleanup efforts. Here we present data collected to support various efforts of the LWBI. For more information, please visit https://www.canada.ca/en/environment-climate-change/services/water-overview/comprehensive-approach-clean/lake-winnipeg/reports-publications/basin-initiative.html.

Permafrost loss is pervasive across northern circumpolar regions. The loss of frozen ground has profound impacts on water resources at varying spatial and temporal scales via changes to predominant hydrological processes, runoff pathways and entrainment rates of solutes and sediments. Consensus exists that permafrost loss will continue, and rates will vary spatially, but how hydrology and biogeochemistry will respond across large swaths of land remains largely unknown. Previous research elucidated small-scale processes or described circumpolar trends, with minimal cross-scale research. In particular, a pan-Canadian assessment of water resource vulnerability to permafrost loss is lacking. This study develops and applies a framework for assessing vulnerability of pan-Canadian water resources to permafrost loss. For the purposes of this study, “water resources” is defined as the surface hydrological and aquatic chemistry regime characterized by water budgets, aquatic chemistry concentrations and loads. The framework was applied in developing the Canadian Water Resources Vulnerability Index to Permafrost Loss (CWRVIPL), including mapping of the index across the Canadian North. The CWRVIPL is a linearly additive index of permafrost, physiographic, disturbance and climatic conditions and stressors that influence water budgets and aquatic chemistry. Initial results imply aspects of water resources in northern Alberta, the Northwest Territories and the Hudson Bay Lowlands are most vulnerable to permafrost loss, and these regions are embedded in a large band of relatively more vulnerable territory extending from the northern Yukon south to James Bay and northeastward to Labrador. In the Arctic Archipelago, water resources in portions of Banks, Victoria and Baffin Islands are also relatively vulnerable to permafrost loss. The index identifies areas of water resource vulnerability on which to focus and encourage ongoing observation and research in the Canadian North.

The study examines the parasite communities in Athabasca River Trout-perch (Percopsis omiscomaycus) at five sites along the main stem of the Athabasca River to explore whether any observed changes in parasite abundance or community structure might correlate with small-scale variations in water chemistry, sediment characteristics, water and sediment pollution, larger-scale landscape use patterns, distance among sites, and upstream-downstream gradients.