Gauges · Reservoirs · Dam Operations · Property Thresholds
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Ottawa River corridorclick a station to jump to its card
Daily briefAI-generated summary of today's basin state
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Watershed snapshot — current levels
Main-stem stations upstream → downstream. Bar height = level (MASL); colour = current flood state; arrows = change over ~24 h and ~72 h. Click a bar to see its 2017/2019/2023 references.
ORRPB daily snapshot — 24:00h water levels
Same 14-station bar chart that gets posted to Facebook each morning. Source: ORRPB "Water levels at 24:00h in metres" table at ottawariver.ca/conditions, scraped daily. Constance Bay (MVCA) and Below Carillon (CEHQ) come from the live feeds since ORRPB doesn't publish them. Colour: rising / falling / no change vs. the prior day.
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Waltham (Ottawa River — upstream)
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Lac Coulonge (Ottawa River)
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Coulonge River tributary at Route 148
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Regional context — Ottawa River corridor
Upstream-to-downstream gauges along the Ottawa River. Upstream stations lead Lac Coulonge by hours-to-days and flag incoming pulses.
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Property thresholds & surveyed flood lines
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Upstream freeze tracker
Overnight lows across the basin — last night plus 6-day forecast. Three freeze nights signals snowmelt is paused or pausing.
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All stations — corridor view
Each card has its own time-series chart, daily change, flood-state badge, ORRPB reference label, percentile (where available), and 48 h precipitation forecast at the nearest weather station. Click a card to open the full detail.
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Reservoir storage — basin-wide
Percent-full of the major Ottawa River basin reservoirs. When upper-basin reservoirs approach 90%, operators lose discretion to absorb new inflow — that's the signal a freshet pulse will pass through to Lac Coulonge instead of being held back.
Level data: ORRPB conditions page, scraped daily. Operating limits: same ORRPB pages (per-location System Constraints tables). Storage capacities: ORRPB / ICOLD-Canada case study (2020), Table 1 — a single authoritative source listing usable storage for all 13 principal cascade reservoirs.
Percent full is estimated using the difference between the published high and low operating limits for each reservoir. The low operating limit represents the minimum level at which a generating station or dam can maintain outflow under normal operating conditions.
A simple linear approximation is applied across this operating range to estimate how full a reservoir is at a given level. This provides a reasonable point-in-time estimate of percent full based solely on water level relative to the operating limits.
Reservoir level data is captured as a point-in-time measurement, while official daily values are typically finalized using 24-hour averaged data. As a result, the percent full displayed on cards reflects current conditions, but the reported daily percent-full value may lag slightly.
Official calculation methods used by reservoir operators may differ and may incorporate additional operational or hydrological factors. For authoritative information, consult the respective reservoir operators. Methodology adapted from Contributor B's community-published reservoir gauge.
Storage volumes shown on each card (e.g. "1,687 / 1,863 M m³") use the usable-storage capacity from Table 1 of the ORRPB / ICOLD-Canada case study (2020) — the single authoritative cascade-regulator source for all 13 principal reservoirs. Click the "[source]" link in any card's detail view to open the citation. Rapide-7 is a small run-of-river headpond fed by the upstream Decelles reservoir (not in the ORRPB cascade table) and has no published usable-storage volume of its own.
⚠ Operating limits are starting estimates from operator documentation — not yet calibrated. Percent-full numbers may drift ± a few points until limits are finalized.
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Tributaries — second-peak watch
Major tributary stations on the rivers that feed the Ottawa downstream of Mansfield.
These don't directly affect Lac Coulonge — but they constrain ORRPB's options at Carillon.
A rising Gatineau forces lower-river outflow up, which propagates upstream as backwater pressure.
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Dam operations — release telemetry
Live discharge from each Hydro-Québec generating station in the Ottawa basin: total release, the share going through the turbines, and the share going over the spillway. A high spilled % means the dam is bypassing power generation to evacuate water — typically because the headpond is at its operating ceiling.
Source: Hydro-Québec open-data feed, ingested hourly to TimescaleDB.
Bryson and Carillon also expose headpond (amont) and tailwater (aval) levels, letting us compute the live head differential — the variable at the heart of the Mansfield case file.
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Main-stem river flow — ORRPB · avg daily, m³/s, upstream→downstream · incl. the OPG dams (Otto Holden / Des Joachims / Chenaux / Chats Falls) absent from the HQ feed below · source
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Hydro-Québec releases — Ottawa main stem (upstream → downstream)
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Gatineau cascade (joins Ottawa at Hull)
Lower St-Lawrence (downstream of Carillon)
Wave propagation — three views
The Ottawa is a system, not a place. A freshet pulse that hits Témiscaming arrives at Carillon several days later — the river carries the wave downstream as a physical signal. Each panel below tells the same story with a different visual grammar; this page exists so the community can tell us which is most useful.
Source: mean daily discharge (m³/s) from the ORRPB main stem (Témiscaming → Carillon), backfilled from ORRPB's per-location archive for the past year. Pick a window below — short windows show the current 2026 freshet, longer windows include the 2025 freshet and summer/fall recession for context.
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1 · Multi-line time series · last 30 days · one line per station
The familiar form. Magnitude differences (upstream = thinner river, downstream = bigger) and day-to-day changes are both readable, but you have to mentally trace each line to spot the wave moving downstream.
2 · Stacked small multiples · each panel = one station · top is upstream, bottom is downstream
The page itself becomes a map of the river. Watch the peak march down the stack — what you see at the top arrives at the bottom several days later.
3 · Hovmöller heatmap · station × day · color = flow (per-station normalized)
A meteorologist's tool, repurposed. Stations stack vertically (upstream at top), days run left-to-right. A diagonal stripe of bright cells is the freshet wave moving through the system — its slope tells you the direction. A textbook upper-basin snowmelt freshet would slope down and to the right (upper stations peak first, lower later). On longer windows that include 2026 you'll see the opposite: the stripe slopes up and to the right because the lower-basin tributaries (Gatineau, Madawaska, etc.) peaked around Apr 21-22 while upper-basin Témiscaming didn't peak until May 2. The slope is the story of where the water came from. Each row is normalized to its own station so smaller upstream stations stay legible alongside Carillon.
Which of these did you find clearest? Let us know in the community discussion — the most useful view will be promoted into the main Overview tab.