Forecasts
Publication: 2026-04-19 4:00 PM
*** TO SEE HISTORICAL PEAKS - GO TO "CURRENT CONDITIONS" PAGE **** This map includes markers representing the locations where the Ottawa River Regulating Committee provides hydrological forecasts to the public. During the spring freshet, forecasts are updated Monday to Friday, unless specified otherwise by the date stamp “Next Update” in the River Conditions Forecast message. *** IF THE PAGE DOESN'T DISPLAY CORRECTLY, TRY REFRESHING or VIEW THE FRENCH VERSION ***
Forecast Values
| Location | Type of value |
2026-04-19 (Forecast) |
2026-04-20 (Forecast) |
2026-04-21 (Forecast) |
2026-04-22 (Forecast) |
|---|---|---|---|---|---|
| Ottawa River at Temiscaming Graph View | Flow (m3/s) | 1300 | 1500 | 1600 | 1800 |
| Ottawa River at Mattawa Graph View | Level (m) | 153.45 | 153.65 | 153.80 | 154.10 |
| Ottawa River at Pembroke Graph View | Level (m) | 113.10 | 113.10 | 113.10 | 113.10 |
| Lake Coulonge at Fort-Coulonge Graph View | Level (m) | 108.50 | 108.55 | 108.60 | 108.55 |
| Chats Lake at Arnprior Graph View | Level (m) | 75.65 | 75.65 | 75.70 | 75.65 |
| Lake Deschenes at Britannia Graph View | Level (m) | 60.10 | 60.20 | 60.25 | 60.25 |
| Flow (m3/s) | 4410 | 4750 | 4900 | 4900 | |
| Ottawa River at Gatineau (Hull) Graph View | Level (m) | 44.15 | 44.40 | 44.50 | 44.50 |
| Ottawa River at Thurso Graph View | Level (m) | 42.80 | 42.90 | 43.00 | 43.00 |
| Ottawa River at Carillon Graph View | Flow (m3/s) | 7200 | 7300 | 7450 | 7350 |
River Conditions Forecast
Water levels and flows continue to rise at all locations along the main stem of the Ottawa River as significant runoff from rainfall and snowmelt from the unregulated portion of the basin flow into the river. Reservoirs are retaining spring runoff to reduce flooding in the dowstream river system. Minor flood levels have been exceeded in most flood prone areas along the Ottawa River from Pembroke down to Carillon. Major flood levels from Lake Coulonge to Carillon have been exceeded or are expected to be exceeded tomorrow or Tuesday. The minor and major flood levels are defined on the Home page in the Special Feature section. Levels should continue increasing over the next few days in all locations and start stabilizing on Monday. Our website Forecasts section provides expected water levels over a four-day horizon in several areas. Uncertain weather factors play into estimating peak levels over the coming week. On April 19 peak level estimates are generally above 2025 peak levels but below 2023 peak levels, as follows: Pembroke (113.10 m), Lac Coulonge (108.60 m), Chats Lake (75.70 m), Lake Deschenes (60.25 m), Gatineau -Hull marina (44.50 m) and Thurso (43.00 m). These exceed 2025 peak levels by 25 cm (Pembroke), 45 cm (Lake Coulonge), 45 cm (Chats Lake), 50 cm (Lake Deschenes/Britannia), 95 cm (Gatineau -Hull marina) and 70 cm (Thurso). Over the next two weeks, levels are expected to plateau or slowly decline depending on weather. Risk of further increase in levels over coming weeks is higher from Mattawa to Lake Coulonge given the high snowpack remaining in the northern part of the basin.
Instruction:
During the spring freshet period, you may click on any marker to see additional information for this location and to access a Graph View of the data. Graph View is also accessible by clicking on any location in the table below.
- Level forecasts correspond to predicted level at the end of the day (11:59pm) on the specified date.
- Discharge forecasts correspond to predicted average daily discharges for specified dates.
- Note that water levels are measured in metres above mean sea level.
- The water levels forecasts do not account for local variations due to WIND and WAVES effects.
Please read the important warning below.
To find out how the Ottawa River Regulating Committee communicates important hydrological information about the Ottawa River to responsible provincial authorities, please click here.
Warning:
- These forecasts are prepared by the Ottawa River Regulating Committee to inform the collaborative management of principal reservoirs within the Ottawa River basin. These forecasts are used by provincial and federal government responsible authorities to assess flood risks. Only these authorities are responsible for disseminating forecasts to the public.
- These forecasts are based on the anticipated effect of reservoir regulation and on hydrological forecasting of natural inflows for a given weather forecast.
- Absolute accuracy of weather forecasts cannot be guaranteed. In addition, there are inherent uncertainties in the hydrologic models used to estimate inflows and the measurements of water levels and flows at various locations.
- The degree of uncertainty of these forecasts increases with the length of the forecasting horizon.
- Except in unusual circumstances, the table is updated in the afternoon and only on business days.
- The flow rates and actual levels can change rapidly without warning, particularly during the freshet period. We advise those using bodies of water to exercise caution and to always follow established safety guidelines when near water.
- Users of the flow data, water level data, and hydrological forecasts shown on this website must recognize that such information is considered preliminary data. Users must therefore accept that the information provided carries an unspecified level of uncertainty and are advised to be cautious if they intend to use the information for decision-making. Please see the disclaimer for further details.