Flood Watch

Message Number:    2024-03

Issued:                   March 7, 2024, at 3:00 PM EST

From:                      NBMCA Duty Officer, Angela Mills

FLOOD WATCH notifies that the potential for flooding exists within specific watercourses and municipalities. Municipalities, emergency services and individual landowners in flood-prone areas should prepare.

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 FLOOD WATCH has been issued for the North Bay-Mattawa Watershed, EXCEPT Lake Nipissing Shoreline and the Ottawa River at Mattawa

Current Conditions:

Moisture content of the snowpack was 61 mm (as of Mar 1). Warm temperatures over the past week have triggered extensive melt. Water levels in area rivers have increased in response. Water level is high for this time of year on local creeks and rivers, including Chippewa Creek, the La Vase River, and Wasi River. Water level is normal on the Ottawa River at Mattawa and Lake Nipissing.

Current water levels can be viewed by searching Station Names “Ottawa River”, “Mattawa River”, “Chippewa Creek”, “La Vase 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

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

Forecasted Conditions:

A precipitation event is forecast to bring 20-35 mm of rain followed by 5-10 cm of snow beginning late Friday (Mar 8) through Saturday. Daytime high temperatures are forecast to be between 6 and 11 ºC on Friday and Saturday and dipping below freezing for Sunday into Monday. Temperatures are expected to rise again early next week, with no further precipitation.

The water level of Lake Nipissing is expected to continue to slowly increase. 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 may increase over the coming week, per the Ottawa River Regulating Committee.

Historic Flood Conditions:

For comparison, when flooding occurred in the watershed around April 18, 2019, the snowpack water content was 123 mm (measured April 15, 2019). Daytime temperatures were between 3 and 12 °C, with overnight temperatures above freezing. Actual precipitation measured on April 18, 2019 was 31.8 mm. When combined with snowmelt, the daily average water level on Chippewa Creek, in North Bay, increased by 57.6 cm in that one day.

Risk:

A considerable rain event is forecast for this weekend. Rain on frozen or saturated soils quickly becomes runoff. Any remaining snow and ice will contribute additional flow. Water levels in urban areas respond rapidly, especially during and after periods of intense precipitation. Water levels and flows in area creeks are already high from recent snowmelt. The forecast rain has the potential to trigger flooding particularly in the urban areas in the City of North Bay.

Higher flows can break up ice on streams and rivers that are not yet ice-free. Water levels are expected to increase throughout the watershed; however, widespread 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) Monday, March 11, 2024 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  

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:

  • Chippewa Creek
  • Lake Nosbonsing Dam
  • Mattawa River at Hurdman Dam
  • Parks Creek
  • Trout Lake
  • Turtle Lake
  • Talon Lake

Is your property at risk of flooding?

If you think that your property may be at risk of flooding, please contact your municipality.  

If you live in an unorganized township, contact Ministry of Natural Resources and Forestry District office at 705-475-5501.