FLOOD WATCH – Lake Nipissing Shoreline in North Bay and Callander and Mattawa River below Hurdman Dam
Flood Outlook – elsewhere in NBMCA watershed
Message Number: 2024-07
Issued: April 15, 2024, at 4:00 PM EDT
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.
Watershed Conditions Statement – Flood Outlook gives early notice of the potential for flooding based on weather forecasts calling for heavy rain, snow melt, high wind or other conditions that could lead to high runoff, cause ice jams, lakeshore flooding or erosion.
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 Lake Nipissing Shoreline in the City of North Bay and Municipality of Callander.
A FLOOD WATCH remains in effect for Mattawa River downstream of Hurdman Dam to the confluence with the Ottawa River in the Town of Mattawa.
A Watershed Conditions Statement – Flood Outlook remains in effect for the remainder of the North Bay-Mattawa watershed.
This is an update to the previous Message Number 2024-06 dated April 13, 2024.
Current Conditions:
Water levels and flows have responded significantly to rain over the last two days. Total rainfall recorded at the North Bay Airport for April 11-13 is 69 mm.
The water level on Lake Nipissing at North Bay has risen by 32.5 cm since April 12 in response to increased inflows. The water level on Lake Nipissing is regulated by dams operated by the federal government.
The water level on the Ottawa River at Mattawa has increased with increased discharge from upstream reservoirs and has receded slightly. The water level on the Ottawa River at Mattawa is forecast to remain stable. Water levels on the Ottawa River are managed by upstream dams and reservoirs operated by provincial and federal governments through the Ottawa River Regulation Committee.
Water levels along the Mattawa River have also increased significantly and have peaked. Water levels on Trout Lake, Turtle Lake, and Lake Talon are high while Lake Nosbonsing and Chant Plein Lake are normal for this time of year. Water levels on Trout Lake, Turtle Lake, and Lake Talon are regulated by dams that are operated by the Ministry of Natural Resources and Forestry.
Water levels on other area rivers have also peaked and have been receding for the past several days.
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:
Minimal precipitation is forecast for the next few days. A light precipitation event is forecast for Thursday (April 18) with easterly winds.
The water level of Lake Nipissing is expected to rise. Public Services and Procurement Canada are advising caution with rising water levels. For water level and flow information, see https://www.tpsgc-pwgsc.gc.ca/ontario/eaux-water/renseignement-information-eng.html. 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 stabilize with flows from upstream, per the Ottawa River Regulating Committee https://ottawariver.ca/
Water levels and flows are expected to remain high in most other areas for the coming days. Streams that usually respond quickly to precipitation events may return to baseflow conditions. Soils are expected to remain near saturated and area rivers will respond rapidly to additional precipitation.
Historic Flood Conditions:
For comparison, in response to 34.5 mm of steady rain over 12 hours with frozen or saturated soil conditions and minimal remaining snowpack in March 2024, the water level on Chippewa Creek increased by 83 cm over 15 hours, peaking about 3 hours after rain ended.
Additionally, when river-based flooding occurred at Mattawa in May 2023, peak flow from the upstream Otto Holden Dam was 32 % greater than current flow and peak flow in May 2019 was 71 % higher than current flow.
Risk:
A Flood Watch has been issued for the Lake Nipissing Shoreline in the City of North Bay and Municipality of Callander. The water level on Lake Nipissing continues to rise in response to increased inflows after last week’s significant rain event. Strong winds and wave action are a concern while lake levels are high. Lower reaches of Lake Nipissing tributaries (such as Chippewa Creek, Parks Creek, Jessup’s Creek, and La Vase River) will be impacted by high water levels on Lake Nipissing. For water level and flow information, see https://www.tpsgc-pwgsc.gc.ca/ontario/eaux-water/renseignement-information-eng.html. 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.
A Flood Watch Continues for the Mattawa River below the Hurdman Dam to the confluence with the Ottawa River at Mattawa. Water levels and flows from the Ottawa River are expected to stabilize per the Ottawa River Regulating Committee. Water level and flow from the Mattawa River has begun to recede. The Ottawa River water levels are managed by dams and reservoirs operated by provincial and federal governments. The Ottawa River Regulation Planning Board posts current data and forecasts on their website https://ottawariver.ca/
A Watershed Conditions Statement – Flood Outlook has been issued for the other areas of the North Bay-Mattawa watershed. Water levels have responded to last week’s significant rainfall event. Water levels and flows have peaked in most areas and have begun to recede but remain high in many areas. Strong winds and wave action are a concern while lake levels are high. Flooding may occur in low-lying and poorly drained areas. Additional precipitation on saturated soil conditions will quickly trigger a response in water levels and flows.
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 fast moving and cold open water, pose a serious hazard. The public is encouraged to keep children and pets away from watercourses and 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, April 19, 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.
https://www.nbmca.ca/watershed-management/flood-forecasting/flood-watch-status-terminology/
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:
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.