FLOOD WARNING for Lake Nipissing Shoreline (Callander and North Bay), La Vase River downstream of Lakeshore Dr, Parks Creek, and Mattawa River downstream from Hurdman Dam (updated)

Message Number: 2026-14

Issued: May 7, 2026 at 9:15 AM EDT

From: NBMCA Duty Officer, Angela Mills

FLOOD WARNING: notifies that flooding is imminent or already occurring in specific watercourses or municipalities. Municipalities and individuals should take action to deal with flood conditions. This may include road closures and evacuations.

If you need assistance responding to 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 FLOOD WARNING remains in effect for the Lake Nipissing Shoreline, La Vase River downstream of Lakeshore Dr, Parks Creek, and the Mattawa River downstream of Hurdman Dam. The Watershed Conditions Statement- Flood Outlook for the remainder of the watershed has ended.

This Message is an update to the previous Message Number 2026-13 dated April 30, 2026.

Current Conditions:

There has been minimal precipitation over the past week. Water level on Lake Nipissing at North Bay is 14 cm above the maximum non-damage elevation. Isolated areas of snowmelt continues in northern parts of the Lake Nipissing watershed. High water on Lake Nipissing directly impacts water levels in the La Vase River downstream of Lakeshore Dr and Parks Creek. The Parks Creek Backflood Control Structure is operational, keeping water levels lowered in the Parks Creek watershed. Eva Wardlaw Conservation Area is closed to the public while operations remain ongoing.

Upstream flows on the Ottawa River, which directly impacts water level in the lower reaches of the Mattawa River, have begun to decrease. Water level in Mattawa peaked 6 cm above the major flood threshold of 154.8 m. Daily average water level has receded by 24 cm. Mattawa Island Conservation Area remains closed due to flooding.

Water levels in other local watersheds have receded to normal for this time of year. Corbeil Conservation Area remains closed until staff can assess the safety of the pedestrian bridge that was damaged during flooding.

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:

Weather forecasts anticipate 10-15 mm of rain in the next five days, mostly on Saturday (May 9). Moderate winds are forecast to be predominantly from the west or southwest for the next five days.

The water level of Lake Nipissing has stabilized, but conditions in North Bay and Callander may be influenced by wind effect. Public Services and Procurement Canada is forecasting water level on Lake Nipissing to remain stable for the next few days, however, this does not account for the potential impact of winds and the watershed is vulnerable to future precipitation events. 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. https://www.canada.ca/en/public-services-procurement/services/infrastructure-buildings/bridges-docks-dams/frenchriver-dam.html

Sustained high flows on the Ottawa River are anticipated as snowmelt continues in the northern areas of its watershed, sending more spring runoff downstream, however these flows are slowly decreasing. In Mattawa, water levels are forecast to continue decreasing by about 10 cm per day, per the Ottawa River Regulating Committee. 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/

Historic Flood Conditions:

Total precipitation March 1 to April 15 are at 50-year highs. Precipitation in March was 200% of normal and precipitation in April was 253% of normal.

For comparison, when river-based flooding occurred at Mattawa in May 2019, the water level on the Ottawa River at Mattawa reached a maximum level of 155.635 m, which is 77 cm higher than the observed peak on April 30. Flow from the Otto Holden dam in May 2019 was around 23% greater at their maximum than present. Comparing historic annual maximum daily average water level, conditions in Mattawa for April 30, 2026, was the tied for sixth (same as 1922) highest since 1918; 2019 was the fourth highest.

Additionally, when lake-based flooding occurred on Lake Nipissing in May 2019, the water level on Lake Nipissing at North Bay reached a maximum daily average level of 196.579 m, which is about 22 cm higher than the present level. The water level was higher than current levels for the period between May 9 and June 8, 2019. Water level is currently 10 cm higher than the 2024 peak elevation. Comparing historic annual maximum daily average water level, conditions for Lake Nipissing in North Bay for May 5, 2026, were the sixth highest since 1933 (three years missing); 2019 was the fourth highest.

Risk:

A Flood Warning continues for the Mattawa River downstream of Hurdman Dam. High flow on the Ottawa River directly impacts water level of the Mattawa River. Water levels are forecast to continue to slowly decrease over the next few days.

A Flood Warning continues for the Lake Nipissing shoreline in North Bay and Callander and includes the La Vase River downstream of Lakeshore Dr and Parks Creek. Water level has stabilized on Lake Nipissing, however, west winds enhance water level on the eastern side of Lake Nipissing and in Callander Bay. High winds over open water combined with high water level water will increase wave action and increase risk for shoreline erosion and damage. Operations are ongoing with the Parks Creek Backflood Control Structure to prevent high water levels on Lake Nipissing from impeding drainage from Parks Creek and surrounding urban areas.

With soils near saturation, especially in the northern parts of the Lake Nipissing and Upper Ottawa River watersheds, water levels could respond rapidly to any additional rain.

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 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) Tuesday, May 12, 2026, at 4:00 PM EDT.

See also the Ministry of Natural Resources – North Bay District local bulletins for areas outside the North Bay-Mattawa Conservation Authority, including for the Ottawa River https://www.lioapplications.lrc.gov.on.ca/webapps/swmc/flood-forecasting-and-warning-program/

Current Flood Forecasting Media Release

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: