Frequently Asked Questions

What is available on this Site?

This site presents 'real-time' hydrometric (water quantity) data measured at over 1700 stations on rivers, streams and lakes across Canada. The main water quantity variables are water level and streamflow.

Users can browse a list of stations or use a map to select stations of interest and to view current water level or streamflow conditions at these stations. The real-time water quantity data are presented in simple graphical and tabular formats. The user can also access historical water level and streamflow data.

Users can also customize a 'my station list' and display data summaries for stations of interest. This feature allows the users to quickly check water level or streamflow conditions at their stations of interest each time they return to the website.

What does "real-time" mean?

Using a sophisticated telecommunications system, water level and streamflow conditions at over 1700 hydrometric stations can be reported on this website within hours of their measurement. This is referred to as "near real-time".

The data are transmitted by satellite or by land-line (telephone) directly from the gauging station to regional data centres. Satellite transmissions are scheduled every 1 to 3 hours. The "polling" of land-line stations is done as often as once every hour or as little as once every day, depending on the requirement.

Data transfer between the regional data centres and this website occurs on a scheduled basis every hour.

Who is responsible for this website?

This site is maintained by the Water Survey of Canada (WSC), Environment Canada. The WSC is the federal agency responsible for the collection, interpretation, and dissemination of standardized water quantity data and information in Canada. The WSC operates the network of hydrometric monitoring stations on behalf of most provinces and all territories, under federal-provincial or federal-territorial agreements. In the case of Quebec, the province collects water quantity data under a similar agreement.

How do we measure water level and streamflow?

The Water Survey of Canada uses state-of-the-art monitoring equipment and methods to collect and process the hydrometric data. At each station, water level data are recorded continuously in digital form using an automated electronic recorder, or "data logger".

A hydrometric technologist visits the station several times a year to take measurements of water depth and velocity, which are required to determine the rate of flow, or discharge, of the river. The technologist takes these measurements from a bridge, by wading in a stream, by boat, or using a cableway strung across a river.

Once a relationship between water level and flow (discharge) has been established, flow data are routinely estimated from the recorded water level data.

In the office, the WSC technologists review and finalize the data under a rigorous quality management process. The data are stored in the national database and disseminated to users via the web.

There are approximately 2650 active hydrometric stations, all recording data on site. However, only about two thirds of these stations transmit data to this website in real-time, using either satellite or telephone communications systems.

What do the data symbols mean?

E - Estimate

The symbol E indicates that there was no measured data available for the day or missing period, and the water level or streamflow value was estimated by an indirect method such as interpolation, extrapolation, comparison with other streams or by correlation with meteorological data.

A - Partial Day

The symbol A indicates that the daily mean value of water level or streamflow was estimated despite gaps of more than 120 minutes in the data string or missing data not significant enough to warrant the use of the E symbol.

B - Ice conditions

The symbol B indicates that the streamflow value was estimated with consideration for the presence of ice in the stream. Ice conditions alter the open water relationship between water levels and streamflow.

D - Dry

The symbol D indicates that the stream or lake is "dry" or that there is no water at the gauge. This symbol is used for water level data only.

R - Revised

The symbol R indicates that a revision, correction or addition has been made to the historical discharge database after January 1, 1989.

How do ice conditions affect water level and discharge data values?

What is "Save List" and how do I use it?

Saving a List

The "Save List" function enables users to save a list of user-selected stations, from the results of a station or location query. Each saved list can contain up to 50 stations, and each user is allowed to save up to 20 lists, please note spaces are not allowed in Save List names.

Retrieving Saved Lists

Once a user has saved a selected list of stations, they can be retrieved by selecting the Save List tab. A listing of a user's "Saved Lists" will be given. Selecting one of the lists will load that list's stations into a query results page. From this results page, the user can select any of the displayed stations for further graphical or tabular viewing.


Please note that a persistent cookie is used to store your Save Lists on your hard drive. The first time you try to save the list, you will be asked if you agree to persistent cookies. If you decline, your station list will not be saved.

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