Water Safety Statement - North Bay-Mattawa Watershed

Message Number: 2025-04

Issued: March 21, 2025, at 12:00 PM EDT

From: NBMCA Duty Officer, Angela Mills

Watershed Conditions Statement – Water Safety: indicates that high flows, unsafe banks, melting ice or other factors could be dangerous for users such as anglers, boaters, swimmers, children, or pets. Flooding is not expected.

If you have a flood emergency, please contact your municipality. If you live in an unincorporated township, please contact the Ministry of Natural Resources (MNR) – North Bay District.

A Watershed Conditions Statement – Water Safety is in place for the North Bay-Mattawa watershed. The previously issued Flood Watch has ended.

This is an update to the previous Message Number 2025-03 dated March 18, 2025

Current Conditions:

Water levels on area lakes and rivers are generally high for this time of year in response to recent snowmelt and rain. Current water levels are normal for spring freshet in April. Much of the snow has melted since the last snow survey on March 14. The next snow survey is scheduled for March 24.

Water level for Lake Nipissing and the Ottawa River at Mattawa are normal for this time of year and are well below flood thresholds.

Current water levels can be viewed by searching Station Names “Ottawa River”, “Mattawa River”, “Chippewa Creek”, “La Vase River”, “Wasi River”, and “Lake Nipissing” at https://wateroffice.ec.gc.ca/search/real_time_e.html

Forecasted Conditions:

Temperatures are forecast to be cooler for the coming week, with daytime highs near or slightly above freezing, and lows below freezing. Any precipitation is forecast to be in the form of snow. This will slow the movement of water through the watershed. Water levels and flows on rivers are expected to continue to decrease with these cooler temperatures.

Water levels on the Ottawa River are managed by upstream dams and reservoirs operated by provincial and federal governments. Forecasts are available at https://ottawariver.ca/

The water level on Lake Nipissing is regulated by dams operated by the federal government. Forecasts are available at https://www.canada.ca/en/public-services-procurement/services/infrastructure-buildings/bridges-docks-dams/frenchriver-dam.html

Risk:

Water levels have increased across the watershed with recent snowmelt. Ice is breaking up along these rivers with faster flows. Changing water levels and recent warmth and rain are deteriorating ice conditions on local lakes.

All residents, especially those in low lying areas, are encouraged to monitor the conditions that are developing. Banks adjacent to rivers and creeks are very slippery at this time and when combined with faster flows and cold open water, pose a serious hazard. The public is encouraged to keep children and pets away from watercourses and off waterbodies.

Municipalities are encouraged to monitor water crossings for debris that may affect the movement of water through culverts and bridges. A close watch on local conditions and updated forecasts and warnings from Environment Canada is also recommended.

Staff at the North Bay-Mattawa Conservation Authority will continue to monitor weather and watershed conditions and update this message based on the changing weather and streamflow conditions.

This message will be in effect until (or updated before) Friday, March 28, 2025 at 4:00 PM EDT.

The general public is advised of these messages through the www.nbmca.ca website with the flood status icon and a link to information about current conditions. NBMCA also circulates these messages to local media and social media, posting on Twitter (@theNBMCA), Instagram (nbmcainfo), and Facebook (NBMCA).

The public is invited to share photos of watershed conditions on social media using #NBMCAFlood.

Media Release issued March 21, 2025

https://www.nbmca.ca/watershed-management/flood-forecasting/flood-watch-status-terminology/

North Bay-Mattawa Conservation Authority Subwatershed map — *^{NBMCA Subwatershed Map}*

Lake Nipissing

Flows through the dams are based on daily analysis of the current status of the lake and river and as agreed to by the Sturgeon-Nipissing-French-Wanapitei Water Management Group. Weather forecast is considered, along with the inflows from the upper watersheds and outflows through the dam to the French River.

You can view the current level on Lake Nipissing at North Bay on the graph below and the French River at the Water Survey of Canada (WSC) website. Fluctuations in the levels are a result of the strong winds affecting the movement of surface water. Water level and flow information for the South River and Sturgeon River systems is available from Ontario Power Generation (OPG).

Flood warnings for Ontario can be found on the Ontario Flood Forecasting and Warning website.

Why the fluctuation in water level readings on Lake Nipissing? Lake Nipissing can sometimes act like a bathtub, with water shifting in the lake, depending upon wind direction, speed and atmospheric pressure - known as a wind surge or seiche. At times the wind can have such an impact that it may result in the level being higher or lower at the French River gauge compared to the gauge located on the North Bay shoreline.

Mattawa River

The current Ottawa River water level may be viewed at the Water Survey of Canada (WSC) website (note that there is a delay of several hours, and 100m should be added to the gauge reading for metres above sea level).

The Ottawa River Regulation Committee and Ontario Power Generation which operates the Otto Holden Dam provide information online regarding the management of water levels on the Ottawa River. To view water levels and current conditions on the Ottawa River visit the Ottawa River Regulation Planning Board and Ontario Power Generation.

Watercourses and Monitoring throughout the Watershed

There are other watercourses within the NBMCA jurisdiction which are monitored by NBMCA and other agencies. These gauges are maintained by Water Survey Canada - Environment Canada and can be viewed in real-time online.

In addition to the Water Survey of Canada gauges, there are other staff gauges which are monitored by NBMCA or the Ministry of Natural Resources and Forestry: