LakeScout

LakeScout interprets raw water-level gauge readings by comparing them to historical data for the same calendar date. This produces a seasonal-percentile position that answers the question: “Is this lake higher or lower than it usually is at this time of year?”

Percentile computation

For each lake's primary gauge station, we compute percentile breakpoints (p10, p25, p50, p75, p90) for each day of the year using the HYDAT historical daily mean water levels. A 7-day rolling window smooths day-to-day variability while preserving seasonal trends.

Status labels

• Unusually low — below the 10th percentile
• Lower than usual — between the 10th and 25th percentile
• Normal — between the 25th and 75th percentile
• Higher than usual — between the 75th and 90th percentile
• Unusually high — above the 90th percentile

Reference value

The current water level is derived from a rolling 6-hour mean of recent readings where available, falling back to the latest single reading. This smooths short-term fluctuations from wave action, boat traffic, or lock operations.

Current vs. history normalization

Current readings are instantaneous (typically every 5–15 minutes). Historical records are daily means from the HYDAT database. Comparing an instantaneous reading against a daily-mean percentile introduces minor uncertainty — an instantaneous reading might differ from the day's eventual mean by a few centimetres. The status labels and gauge bar account for this by using wide percentile bands rather than precise thresholds.

Trend detection

The 7-day trend compares the latest reference value to the value from 7 days ago. A change of more than 2 cm is classified as “rising” or “falling”; smaller changes are labelled “stable”.

All hydrometric data comes from Environment and Climate Change Canada (ECCC), accessed via the GeoMet OGC API and the HYDAT historical database.

Realtime data is provisional and may be revised by ECCC at any time. Historical data comes from the published HYDAT archive.

LakeScout is an informational tool, not a navigation or flood-warning service.

Water level interpretations are provided for general interest only. Do not use this data for navigation, flood response, or any purpose where incorrect information could cause harm. Always consult official sources for safety-critical decisions.

The accuracy of our interpretations depends on the quality and timeliness of ECCC gauge data. Readings may be delayed, incomplete, or incorrect. We make reasonable efforts to detect and flag stale data, but cannot guarantee completeness.

• Covers British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Québec, Yukon, Northwest Territories, and Nunavut.
• Some lakes use outlet or nearby-river gauge stations as proxies. The station relationship is disclosed in the technical details section of each lake page.
• Lakes with fewer than 10 years of historical data produce lower-confidence percentile estimates. This is noted where applicable.
• Instantaneous readings compared against daily-mean percentiles introduces minor uncertainty (typically <3 cm).
• Controlled/regulated lakes may show patterns that differ from natural seasonal cycles. The interpretation engine does not currently distinguish regulated from unregulated lakes.