FLOOD WARNING – Lake Nipissing Shoreline in North Bay and Callander and Parks Creek subwatershed

Flood Watch – La Vase River downstream of Lakeshore Drive and Wasi subwatershed

Flood Outlook – elsewhere in NBMCA watershed

Message Number: 2024-10

Issued: April 24, 2024, at 3:00 PM EDT

From: NBMCA Flood 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.

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 WARNING continues for the Lake Nipissing Shoreline in the City of North Bay and Municipality of Callander and Parks Creek subwatershed.

A FLOOD WATCH has been issued for the La Vase River downstream of Lakeshore Drive and the Wasi River subwatershed.

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 2024-09 dated April 19, 2024.

Current Conditions:

Month-to-date, the North Bay area has recorded 142 mm of precipitation which is approximately 200 % of normal for the month of April.

Water levels on Lake Nipissing are above the maximum “non-damage” water level for Lake Nipissing. Strong winds have amplified water levels in the North Bay and Callander area and have triggered significant wave action. Winds may locally influence average water levels by 10-20 cm. The water level on Lake Nipissing is regulated by dams operated by the federal government.

High water levels on Lake Nipissing influence water level and flow in the lower reaches of tributaries. The Parks Creek Backflood Control Structure is in operation to maintain water level in Parks Creek lower than that of Lake Nipissing, protecting many local homes and businesses from flooding. Water level in the La Vase River downstream of Lakeshore Drive is high.

The water level on the Wasi River remains higher than water levels prior to the significant rain from April 11-13.

The water level on the Ottawa River at Mattawa has increased in response to increased flow from upstream reservoirs. 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 in the remainder of the watershed near 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.

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:

Winds for the next couple of days are expected to be from the North and be calmer than they have been since last week. A significant multi-day rain event is forecast to begin on Saturday (April 27). Forecasts indicate total rainfall of near 50 mm is possible, but storm tracks and total precipitation remain uncertain.

The water level of Lake Nipissing is above maximum non-damage water levels and has been rising. Wind can have a significant effect on the lake, causing large local variations (in the range of 10-20cm water level locally) depending on wind direction, per Public Services and Procurement Canada. 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 also 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.

Landscape conditions with dormant vegetation and saturated soils have limited capacity to store additional moisture. Water level and flow on local lakes and rivers will increase in response to the forecasted rain.

The water level of the Ottawa River at Mattawa is expected to remain stable, though minor flooding in low-lying areas may occur in the next few days, 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:

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 water level that is about 32 cm higher than yesterday’s (April 23) daily average water level of 196.26 m. The water level was higher than current levels for the period between May 3 and June 20, 2019.

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.

Risk:

A Flood Warning continues for the Lake Nipissing shoreline in North Bay and Callander and the Parks Creek subwatershed. Water levels in the downstream reaches of Lake Nipissing tributaries (including Parks Creek, Jessup’s Creek, and La Vase River) are impacted by high water levels on Lake Nipissing. The changes to water levels on Lake Nipissing depend on the amount of water flowing in from rivers, precipitation, wind, and the amount of water flowing out through the control dams to the downstream French River. Average water level on Lake Nipissing continues to rise in response to inflows from the April 11-13 rain event and wind influence. Local water levels can fluctuate rapidly. The North Bay shoreline will experience higher water levels and increased wave action, heightening the risk for shoreline erosion. NBMCA has initiated operations of the Parks Creek Backflood Control structure located at Eva Wardlaw Conservation Area in North Bay. For more information visit: https://nbmca.ca/watershed-management/flood-forecasting/parks-creek-backflood-control-structure/

A Flood Watch has been issued for the La Vase River downstream of Lakeshore Drive. Water level in the La Vase River downstream of Lakeshore Drive is already high with Lake Nipissing’s influence. Increased flow on the La Vase River in response to the forecasted rain could cause flooding for residents along Riverbend Road.

A Flood Watch has been issued for the Wasi River subwatershed. Flow on the Wasi River, though normal for this time of year, remains higher than prior to the April 11-13 rain event, where water level increased by 55 cm and flow increased by 11 m³/s. A similar response to the coming rain event is possible, which may cause flooding in low-lying and flood-prone areas adjacent to the Wasi River.

A Watershed Conditions Statement – Flood Outlook remains in effect for the other areas of the North Bay-Mattawa watershed. Water levels have responded the significant rainfall event from April 11-13. Water levels and flows are near normal for this time of year but remain high in some areas. Strong winds and wave action are a concern while lake levels are high. Flooding may occur in low-lying and poorly drained areas. Landscape conditions with dormant vegetation and saturated soils have limited capacity to store additional moisture. Water level and flow on local lakes and rivers will increase in response to the forecasted 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 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) Wednesday, May 1, 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.

Local flood messages for outside the NBMCA jurisdiction (map below) are issued by the local District Office of the Ministry of Natural Resources and Forestry. All flood messages are posted on the Ontario Flood Forecasting and Warning Program website https://www.lioapplications.lrc.gov.on.ca/webapps/swmc/flood-forecasting-and-warning-program/

Media Release issued April 24, 2024

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: