Surface Water Quantity

Water plays a central role in all activities within a watershed. The rain that falls on the ground flows to the river and sustains all forms of life. All physical and biological activities within a watershed are intimately connected to water. Therefore, the knowledge of its occurrence, distribution, movement and functions is indispensable in understanding a watershed and all the living beings therein.

Within the Rideau Valley, water levels and stream flow, precipitation and snowpack have been systematically recorded for many years.This information can be analyzed to understand various aspects of the water cycle (or hydrologic cycle) and their impacts on the watershed. Monitoring streamflow and precipitation allows water managers to identify risk-prone areas and better respond to drought or flood conditions.

Streamflow & Water Levels

Streamflow and water level data are used to monitor flood and drought events. They are also used to monitor water supply for lake operation and navigation. This information is used to determine flood risk, support land use planning, assess fish habitat and for water quality analyses of contaminant loading.


Streamflow information is collected at 8 different locations along the Rideau River, Jock River, Kemptville Creek, Tay River and Ottawa River. Various agencies (Parks Canada - Rideau Canal Office, Environment Canada - Water Survey Division, Ministry of Natural Resources and Forestry and RVCA) are involved in the collection of the streamflow data.

Water levels

Six water level stations are found throughout the watershed along the Rideau River and on Big Rideau, Bobs, Wolfe and Upper Rideau Lakes. Data is collected using electronic continuous recording units. A sensor reads the water levels usually at one hour intervals and that data is recorded in a “data-logger” that can be downloaded at the site or transmitted to the RVCA by telephone, radio or satellite communication.

Manual measurements of water level can also be done by placing a measuring device or “staff gauge” in the river attached to a bridge or somewhere so that the gauge is always in the water and can be easily read by an observer. Manual measurement of water level are very useful in documenting rare events and calibrating numerical models.


Precipitation is the total amount of water that falls on the ground in the form of rain, snow and hail. Part of the precipitation flows on the ground towards rivers, part of it seeps down into the ground, and part of it goes back to the atmosphere through evaporation and transpiration by plants.

Precipitation information is collected to help understand its impact on streamflows, water levels and low flow conditions. Precipitation data is used by the RVCA in flood forecasting, flood risk assessment and drought analysis and by others for such things as reservoir management, agricultural activities, road system and storm water management and recreation planning.

RVCA looks to six stations where precipitation data is being collected on a long term basis:

  • Ottawa Airport (since 1938)
  • Russel (since 1954)
  • Brockville (since 1965)
  • Drummond Centre (since 1984)
  • Godfrey (since 1981)
  • Kemptville (since 1928)

Additional information is compiled from volunteers who have joined our Rain Gauge Network. We provide the rain gauge and volunteers supply the readings. Learn more about the Rain Gauge Program.


Snowpack is the accumulated snow cover on the ground. A significant portion of the total precipitation that falls on the Rideau Watershed is in the form of snow.

Snow measurements are done on or about the 1st and 15th of each month from the beginning of December to when the snow is gone in March or April. Five locations are monitored by the RVCA in the lower watershed east of Smiths Falls and another six in the upper watershed are monitored by staff of the Rideau Canal Office of Parks Canada.

Contact Us

Rideau Valley Conservation Authority
3889 Rideau Valley Drive
Manotick, Ontario K4M 1A5

613-692-3571, 1-800-267-3504


Monday to Friday, 8:30 a.m. to 4:30 p.m.

Member of: conservation ontario