Historic Bathymetry Maps For Over 11,000 Ontario Lakes

Over 11,000 lakes across Ontario have historic bathymetry maps produced by the Ministry of Natural Resources and Forestry from the 1940s to the 1990s. These paper maps have been scanned into digital files and are being converted to GIS line data for public and specialist use. The data represents a primary source for lake depth information in the region.

Use Cases

• Model climate change impacts on lake ecosystems using historic depth contours and shoreline data.
• Support fish population monitoring and habitat studies by analyzing depth distribution across lakes.
• Create recreational fishing maps by overlaying bathymetry lines with other geospatial features.
• Perform hydrologic cycle and watershed-based water budgeting using lake depth and area metrics.
• Study long-term changes in lake morphology by comparing these historic maps with modern surveys.

Strengths

• Covers over 11,000 lakes across Ontario.
• Provides temporal coverage from the 1940s to the 1990s.
• Represents the only authoritative source for many Ontario lakes.

Limitations

• Depth information may be inaccurate due to natural or constructed events since collection.
• Original maps used simple methods with little effort to identify shoals and hazards.
• Some scanned maps in package 99 have undetermined locations.

Provenance

Source

Government of Ontario, Ministry of Natural Resources and Forestry.

Collection Method

Paper maps created using simple depth measurement methods, later scanned and converted to GIS line data.

Time Range

1940s to 1990s.

Freshness

Last updated in March 2026, with new digital files added as available.

Geography

Lakes across Ontario, Canada.