Early‑May 2025
Setting up docks and ramps before the season begins is always easier when we know how much water we can expect. Many people are dealing with that right now. Current gauge data from Midland, plotted in NautWise GoTime, shows that water levels on 1 May 2025 are about 30 centimetres (one foot) lower than on the same date in 2024. Similar data is also measured and recorded in Collingwood, Tobermory, Parry Sound, Little Current, and Thessalon.
Over the past two seasons, the bay has added only 10–18 cm (roughly 4–7 inches) between early May and its late‑July high. If this normal pattern holds, the summer‑2025 peak will sit 5–10 cm lower than last year and 15–20 cm lower than the 2023 peak.
What the numbers suggest
| Date | 2023 level | 2024 level | 2025 level |
| 1 May | ≈ 176.48 m MSL | ≈ 176.42 m | ≈ 176.12 m |
| Late‑July peak | ≈ 176.58 m | ≈ 176.60 m | Projected 176.38–176.46 m |
Practical considerations for 2025
- Dock height and extensions
Plan for an additional 15 cm (6 in) of clearance compared with last year to keep decks level with boat gunwales in midsummer. - Shallow approach channels
Areas that carried 1.6 m of depth last July could average 1.45–1.50 m this year. Mark hazards and schedule any spot dredging early. - Electronic depth alerts
If you use sonar alarms or app‑based notifications, set them 5 cm lower than your 2024 threshold to receive timely warnings.
(All figures come from the Midland gauge; local depths vary with shoreline profile and wind.)
About the data
The comparison graphics in this post were created with NautWise.com — GoTime. GoTime is designed to help you pick what date or time is best for your chosen activities. (See Post About New Version).
But it also combines real‑time gauge feeds with historic overlays so users can:
- Set your location using the drop-down menu on the Home Page.
- Compare the current season to past years at a glance by double-clicking on the “Water Level Past Year Delta”.
- Create an exact location to estimate depth at your own dock using the Depth Below Draft feature.
- Receive automatic email or push alerts when preset depth limits are reached.
The full NautWise GoTime feature set is available free of charge during the spring launch period. Visit NautWise.com for immediate access.
Staying informed now reduces mid‑season adjustments later. Use the early data to set dock heights, review navigation routes, and program depth alerts before boats go in the water. Safe preparations now will make for a smoother, safer summer on Georgian Bay.
This analysis assumes an average water level. On the day of a trip, check Nautwise to see the value for the day.
The included dock image was created in AI to demonstrate the impact of low water levels and does not represent a real location. The other images were created from the Desktop version of the NautWise GoTime app.