Water Safety – North Bay- Mattawa Conservation Authority watershed jurisdiction

Message Number: 2023-21

Issued: November, 6 2023, at 11:30 AM EST

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 and Forestry (MNRF) – North Bay District.

A Watershed Conditions Statement – Water Safety is in place for all areas of the North Bay- Mattawa Conservation Authority watershed jurisdiction.

Current Conditions:

Water levels on Chippewa Creek, Lake Nipissing, Turtle Lake, Lake Talon, are normal for this time of year. Water levels in other areas including La Vase River, Wasi River, Lake Nosbonsing, and the Ottawa River at Mattawa remain high for this time of year in response to above normal precipitation through October. This has left saturated conditions throughout the landscape. Additional precipitation will trigger runoff quickly.

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.tpsgc-pwgsc.gc.ca/ontario/eaux-water/renseignement-information-eng.html

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:

Forecasts indicate 15 to 25 mm of rain are possible today. With current saturated conditions, water levels and flows are expected to increase across the watershed. Conditions can change quickly in response to intense precipitation.

The changes to water levels on Lake Nipissing depend on the amount of water flowing in from rivers, precipitation, and the amount of water flowing out through the control dams to the downstream French River.

The water level of the Ottawa River at Mattawa is expected to continue to decrease slowly, per the Ottawa River Regulating Committee.

Historic Flood Conditions:

In response to very intense rain on September 17, 2023, Chippewa Creek increased by 113 cm in just 55 minutes, rising with a rate of up to 20 cm every 5 minutes.

Risk:

The forecasted rain through Tuesday morning (Nov. 7) will increase water levels across the watershed.

Saturated conditions combined with additional precipitation may result in rapid changes in water levels on urban creeks in the City of North Bay, especially during and after periods of intense precipitation. Water levels are expected to remain above normal for this time of year in the Ottawa River and lower reaches of the Mattawa River over the next few days. Water levels in the rest of the watershed will also increase in response to the continuing rain event; however, flooding is not expected at this time.

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 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) Wednesday, November 8, 2023 at 4:00 PM EST. - Media Release

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: