Data has been collected primarily using a depth measurement device, such as an echo-sounder, in combination with a GPS for horizontal positioning. Other survey methods, such as bathymetric LiDAR may also have been used. The survey method used in each body of water is shown in the [Bathymetry Index](https://geohub.lio.gov.on.ca/datasets/mnrf::bathymetry-index ). *[GPS]: Global Positioning System

Bathymetry is the measurement of water depth in lakes. From the 1940s to the 1990s, the Ministry of Natural Resources and Forestry produced bathymetry maps for over 11,000 lakes across Ontario. The data can be used by the general public and GIS specialists for: * climate change modelling * fish monitoring and other ecological applications * hydrologic cycle modelling * recreational fishing maps * watershed-based water budgeting The maps were created using simple methods to determine lake depths. They were meant for resource management purposes only. Little effort was made to identify shoals and other hazards when creating these bathymetric maps. Since this data was collected, many constructed and naturally occurring events could mean that the depth information is now inaccurate, so these maps should not be used for navigational purposes. In many cases, these maps still represent the only authoritative source of bathymetry data for lakes in Ontario. __Technical information__ These maps are being converted to digital GIS line data which can be found in the [Bathymetry Line](https://geohub.lio.gov.on.ca/datasets/mnrf::bathymetry-line) data class. The [Bathymetry Index](https://geohub.lio.gov.on.ca/datasets/mnrf::bathymetry-index) data class identifies if GIS vector lines have been created and the location of mapped lakes. The historic paper maps have been scanned into digital files. We will add new digital files to this dataset if they become available. The digital files have been grouped and packaged by regions into 13 compressed (zipped) files for download. Note: package 99 contains scanned maps where the location shown on the map could not be determined.

All available bathymetry and related information for Island Lake were collected and hard copy maps digitized where necessary. The data were validated against more recent data (Shuttle Radar Topography Mission 'SRTM' imagery and Indian Remote Sensing 'IRS' imagery) and corrected where necessary. The published data set contains the lake bathymetry formatted as an Arc ascii grid. Bathymetric contours and the boundary polygon are available as shapefiles.

All available bathymetry and related information for Eden Lake were collected and hard copy maps digitized where necessary. The data were validated against more recent data (Shuttle Radar Topography Mission 'SRTM' imagery and Indian Remote Sensing 'IRS' imagery) and corrected where necessary. The published data set contains the lake bathymetry formatted as an Arc ascii grid. Bathymetric contours and the boundary polygon are available as shapefiles.

All available bathymetry and related information for Reita Lake were collected and hard copy maps digitized where necessary. The data were validated against more recent data (Shuttle Radar Topography Mission 'SRTM' imagery and Indian Remote Sensing 'IRS' imagery) and corrected where necessary. The published data set contains the lake bathymetry formatted as an Arc ascii grid. Bathymetric contours and the boundary polygon are available as shapefiles.

This file contains the water quality data summarized in the 1998 report entitled: Baseline Water Quality Inventory, Curecanti National Recreation Area. The data and locations existed in the United States Environmental Protection Agency's Storage and Retrieval (STORET) water quality database management system when the report was published.

All available bathymetry and related information for Minnie Lake were collected and hard copy maps digitized where necessary. The data were validated against more recent data (Shuttle Radar Topography Mission 'SRTM' imagery and Indian Remote Sensing 'IRS' imagery) and corrected where necessary. The published data set contains the lake bathymetry formatted as an Arc ascii grid. Bathymetric contours and the boundary polygon are available as shapefiles.

This file contains the water quality data summarized in the 1998 report entitled: Baseline Water Quality Inventory, Thomas Stone National Historic Site. The data and locations existed in the United States Environmental Protection Agency's Storage and Retrieval (STORET) water quality database management system when the report was published.

World Bathymetry Base Map tile cache. The service includes world bathymetry data, and ocean, country, population and natural features. The information was derived from various sources, including Natural Earth and National Geophysical Data Center (NGDC) ETOPO2 Global 2 Elevations from the September 2001 data. The service contains layer scale dependencies.

All available bathymetry and related information for Isle Lake were collected and hard copy maps digitized where necessary. The data were validated against more recent data (Shuttle Radar Topography Mission 'SRTM' imagery and Indian Remote Sensing 'IRS' imagery) and corrected where necessary. The published data set contains the lake bathymetry formatted as an Arc ascii grid. Bathymetric contours and the boundary polygon are available as shapefiles.