St. Mary Reservoir

Normal

Water level is right where you'd expect for mid-September and falling.

This is a controlled waterbody (reservoir or regulated lake). Water levels may be managed by dam operations and may not follow natural seasonal patterns.

Low (1079.05m)Normal rangeHigh (1102.52m)

Current Weather

2d ago

22°C

Wind W 9 km/h

Humidity 37%

Sunny

Environment Canada — Cardston - Fort Macleod - Magrath

vs. Last Year

No data available

7-Day Trend

↓Falling

Down 29.1 cm over the past week

-29.1 cm over 7 days

Seasonal Position

52nd percentile

Based on 65 years of records

Seasonal Outlook

Typical next 7 days

This lake usually drops noticeably over the next week.

Typical next 14 days

Over two weeks, levels typically drops noticeably.

Tracking

This year is moving faster than usual.

Based on 61 years of seasonal patterns. This is a historical seasonal pattern, not a forecast.

Lake Profile

Est. average depth13.5 m

Estimated from HydroLAKES v1.0 (Messager et al., 2016). Modeled geo-statistical estimate, not a direct survey measurement.

Water Level — Last 30 Days

Technical details

Current level: 1098.60 m
Reference value: 1098.61 m (rolling_6h_mean)
Percentile for date: 52nd percentile
Years of record: 65
Source station: ST. MARY RESERVOIR NEAR SPRING COULEE (05AE025)
Est. average depth: 13.5 m
Relationship type: controlled_system
Mapping confidence: medium
Today's normal range: 1094.51–1100.55 m
Same-date historical range: 1079.05–1102.52 m
30-day change: -90.6 cm
Data confidence: medium
Observed at: Sep 20, 2026
Last snapshot: Sep 20, 2026

Data source: ECCC Water Office — Station 05AE025. Water level readings are provisional and subject to revision. This is not a navigation or flood-warning service.