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 May 26)

Message Number: 2026-18

Issued: May 26, 2026 at 2:30 PM 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 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 WARNING continues for the Lake Nipissing Shoreline, La Vase River downstream of Lakeshore Ave, and Parks Creek. The previously issued Watershed Conditions Statement – Flood Outlook has ended.

This is an update to the previous Message Number 2026-17 dated May 19, 2026.

Current Conditions:

Water levels on Lake Nipissing continue to be high. Water levels have been fluctuating by +/- 4 cm over the last couple of days and are slowly receding toward the maximum non-damage elevation. Daily average water level has receded by 15.5 cm from the peak on May 5^th.

Water levels on other area lakes and rivers are normal to above normal for this time of year.

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 week which will allow water to drain from the watershed. Water levels and flows are expected to continue to decrease across the watershed.

Moderate winds are forecast from the southwest through today (May 26), possibly gusting to 50-60 km/h and transitioning to north winds for the next few days.

The water level of Lake Nipissing remains above the maximum non-damage elevation. 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

The water level of the Ottawa River at Mattawa has returned to seasonally normal conditions and are forecast to decline gradually as large volumes of water continue to drain from the upper Ottawa River. 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:

Precipitation in March was 200% of normal and precipitation in April was 253% of normal. Month-to-date, precipitation in May is 96% of normal.

For comparison, 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 20.3 cm higher than the observed peak on May 5, 2026. Comparing historic annual maximum daily average water level, peak 2026 level for Lake Nipissing in North Bay was the sixth highest since 1933 (three years missing); 2019 was the fourth highest.

Risk:

A Flood Warning remains in effect for the Lake Nipissing Shoreline, La Vase River downstream of Lakeshore Dr, and Parks Creek which are directly influenced by the Lake Nipissing water levels. Water levels may fluctuate in response to southwest and west winds, which can temporarily enhance local water level by 10-15 cm. While water levels remain high, Lake Nipissing shoreline areas remain vulnerable to winds and wave action may cause erosion.

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, Jun 2, 2026 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.

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: