This mosaic is calculated over the North American domain with a horizontal spatial resolution of 1 km. This mosaic therefore includes all the Canadian and American radars available in the network and which can reach a maximum of 180 contributing radars. To better represent precipitation over the different seasons, this mosaic renders in mm/h to represent rain and in cm/h to represent snow. For the two precipitation types (rain and snow), we use two different mathematical relationships to convert the reflectivity by rainfall rates (mm/h rain cm/h for snow). This is a hybrid mosaic from DPQPE (Dual-Pol Quantitative Precipitation Estimation) for S-Band radars. For the US Nexrad radars, ECCC uses the most similar product from the US Meteorological Service (NOAA). This product displays radar reflectivity converted into precipitation rates, using the same formulas as the Canadian radars.

Monthly, seasonal and annual trends of total precipitation change (millimetres) based on adjusted station data (AHCCD) are available. Trends are calculated using the Theil-Sen method using the station’s full period of available data. The availability of precipitation trends will vary by station; if more than 5 consecutive years are missing data or more than 10% of the data within the time series is missing, a trend was not calculated.

This theme presents the index of water health along the banks of the St. Lawrence River. It makes it possible to determine if the sites present risks to human health and if they are suitable for swimming.These data are the result of an exploratory monitoring program that aims to raise awareness among the population and local actors about the possible reopening of bathing sites that have good potential. This program also makes it possible to highlight any improvement in bacteriological quality resulting from the reduction of wastewater overflows during rainy weather or resulting from the installation of disinfection equipment.**This third party metadata element was translated using an automated translation tool (Amazon Translate).**

The data represents the annual total precipitation in Alberta over the 30-year period from 1971 to 2000. A 30-year period is used to describe the present climate since it is enough time to filter our short-term fluctuations but is not dominated by any long-term trend in the climate. Annual total precipitation refers to rain, snow and other forms of moisture such as hail. Annual precipitation is greatest in the mountains and decreases at lower elevations. In the agricultural areas of the province, 50 to60 percent of annual precipitation generally occurs during the growing season, mostly as rain.Precipitation in any month can be extremely variable with the variability of precipitation being greater in southern Alberta than in the Peace River Region and central Alberta. However, long-term (30-year) data provides a reliable indication of what to expect in any given location. Climate information is used as a long-term planning tool, in selecting a location for a farm or planning a cropping program. Crop producers generally look at the most likely weather conditions rather than the extremes because the key inputs and decisions are made well in advance of achieving results. By combining knowledge of the agricultural operation with knowledge of what is likely to happen (climate), the producer can then decide on the acceptable level of risk due to adverse conditions. This resource was created using ArcGIS

The Adjusted Precipitation data consist of monthly, seasonal and annual totals of daily adjusted rain, snow and total precipitation (millimetres) for 464 locations in Canada. Adjusted precipitation data incorporate adjustments (derived from comparison of instruments) to the original station data to account for discontinuities from non-climatic factors, such as instrument changes or station relocation. The time periods of the data vary by location, with the oldest data available from the early 1880s at some stations to the most recent update in 2017. Observations at co-located sites were sometimes joined in order to create longer time series. Data availability over most of the Canadian Arctic is restricted to the mid-1940s to present.

This polygon layer shows sub-basin averages of HRDPS (High Resolution Deterministic Prediction System) precipitation. Ideal for capturing short-range (0–48h) high-resolution precipitation forecasts aggregated at the watershed scale.The HRDPS is a 2.5 km resolution model used for short-range, convection-permitting forecasts in Canada. This layer takes HRDPS precipitation totals and aggregates them by each sub-basin polygon, revealing how localized rain or snow could impact individual watersheds. Useful for near-term flood or flash-flood risk, as well as local water management during intense weather.

This polygon layer depicts sub-basin average observed precipitation from the High Resolution Deterministic Precipitation Analysis (HRDPA). Offers insight into how much rain/snow actually fell across each watershed in the past observation period. Observation periods we are interested are for past 1 day, 3 days and 7 days.HRDPA is ECCC’s high-resolution precipitation analysis, merging gauge, radar, and HRDPS model data. This layer aggregates the final (or preliminary) HRDPA accumulations to sub-basin polygons. Each record indicates the average precipitation that truly occurred over each watershed, vital for verifying model forecasts, calibrating hydrological models, and conducting post-event analyses of flood or drought severity.

This polygon layer displays ensemble-based, medium-range precipitation forecasts from the Global Ensemble Prediction System (GEPS), offering a probabilistic view of future rainfall or snowfall over a 16‑day horizon. It aids in uncertainty analysis, risk assessment, and strategic resource planning.Ensemble Approach: GEPS runs multiple perturbed members of ECCC’s GEM model, capturing a range of atmospheric evolutions and yielding probability distributions for precipitation. Global Domain: Similar coverage to the GDPS but focuses on ensemble mean, spreads, and probabilities rather than a single deterministic outcome. Longer-Range Outlook: Extends up to 16 days, supporting risk-based planning for potential floods, extended rainfall events, or dryness. Data Utility: Allows decision-makers to weigh confidence levels in precipitation scenarios, vital for water management, agriculture, and emergency contingency strategies.

This polygon layer displays sub-basin-level average precipitation derived from the ECMWF (European Centre for Medium-Range Weather Forecasts) model. This layer helps hydrologists, forecasters, and planners see how much rainfall/snowfall is predicted or has occurred in each sub-basin, supporting medium-range water resource and flood management. We are intersested in the forecast period of 7 days.This layer aggregates ECMWF forecast precipitation over polygonal sub-basins. Each feature includes attributes for average accumulated precipitation, forecast run/valid times, and sub-basin identifiers. ECMWF is a leading global model offering medium-range (up to 10 days) forecasts at a high skill level. By focusing on sub-basins, this layer aids in local-scale decision-making—enabling more precise flood risk assessments, reservoir inflow estimates, and water resource planning across the region of interest.

The sewer system (secondary and main networks) on the Island of Montreal includes 170 overflow structures. An overflow structure consists of an underground control chamber that directs wastewater into the collection and interception network under normal operating conditions to the treatment plant. During rain, melt or during an operation associated with maintenance or impairment, the inputs exceed the regulatory capacity and this excess is overflowed by the structure in question in the watercourses. It is under these conditions that part of the water combining rainwater and wastewater flows to the receiving watercourse for a short period of time (via the outfall). Obviously, the receiving watercourse to the south is the St. Lawrence River and that to the north, the Rivière des Prairies.**This third party metadata element was translated using an automated translation tool (Amazon Translate).**