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.

The dataset has been used for the Great Lakes Conservation Blueprint Project for Aquatic Biodiversity. It can be used for: * research and aquatic species inventories * environmental impact and monitoring * watershed based resource planning and management * fisheries and other aquatic analysis Official GEO title: Aquatic Ecosystems Classification: Great Lakes Basin - Coast, Streams, Lakes and Wetlands

The Waterbodies dataset is comprised of area features: lakes, intermittent waterbodies, islands, and rivers wide enough to be represented as an area feature (e.g. St. Lawrence River, Mackenzie River). In a few exceptional cases, islands had to be represented by "holes" in the polygons in the Waterbodies dataset. Some area features have been subdivided and several types of virtual linear features serve to separate them. Features in this dataset are linked (by an attribute) to their corresponding flow line in the Drainage Network Skeleton. Therefore the Waterbodies dataset may be used in conjunction with the Drainage Network Skeleton for analytical applications. The Islands dataset is comprised of area and linear features: islands within inland waters and the waterbodies and single line rivers within these islands. Oceanic islands are not included as they are part of the coastline component of the Drainage Network Skeleton dataset. The Islands dataset exists to complete the cartographic representation of Canadian hydrology. The Islands dataset is not logically connected with the Drainage Network Skeleton, and can not be used for analytical applications. It should be noted that flow lines of the Drainage Network Skeleton do not take into account of the existence of islands and therefore do not necessarily flow around them. In a few exceptional cases, islands had to be represented by "holes" in the polygons in the Waterbodies dataset. Some islands themselves contain waterbodies and rivers, not significant for network analysis. However, in order to support a complete cartographic representation such waterbodies and rivers have been added to the Islands dataset. The National Scale Frameworks Hydrology data consists of area, linear and point geospatial and attribute data for Canada's hydrology at a national scale. It provides a representation of Canada's surface water features, and data completeness reflects the content of the source, the original Vector Map level 0 (VMAP0) revision 4 hydrographic layers, except where revision editing has been performed. Key value-added characteristics include river flow direction, connectivity and the tagging of geographical name keys to selected rivers, lakes and islands included in the Concise Gazetteer of Canada.The Atlas Frameworks are a set of integrated base map layers which form part of a larger National Scale Frameworks data collection. These data have been compiled at a scale of 1:1 000 000 with the primary goal being to indicate correct relative positioning with other framework layers rather than absolute positional accuracy.Distributed from [GeoYukon](https://yukon.ca/geoyukon) by the [Government of Yukon](https://yukon.ca/maps) . Discover more digital map data and interactive maps from Yukon's digital map data collection.For more information: [geomatics.help@yukon.ca](mailto:geomatics.help@yukon.ca)

Foreshore Plant Habitat Zones for Okanagan region lakes. The purpose of this data is to support the Large Lakes Protocol, an interagency document that addresses the processes that need to be followed during foreshore development. The required application process varies depending on habitat value zone

The Nova Scotia Lake Survey program is a partnership initiative between the Department of Environment and Climate Change and the Department of Fisheries and Aquaculture to inventory lakes throughout the province determining baseline water quality, in support of both sport fisheries and water resource management areas. The following weblink connects to a Department of Environment and Climate Change web map that includes the locations of the monitored lakes within the province and an alternative method for downloading the same lake chemistry dataset: http://nse.maps.arcgis.com/apps/webappviewer/index.html?id=7ded7a30bef44f848e8a4fc8672c89bd"

Kokanee habitat zones for Okanagan region lakes. The purpose of this data is to support the Large Lakes Protocol, an interagency document that addresses the processes that need to be followed during foreshore development. The required application process varies depending on habitat value zone. The data was sourced from Kokanee Shore spawner inventory data

A shapefile of freshwater water bodies hat have been sampled as part of the Nova Scotia Lake Survey. The Nova Scotia Lake Survey program is a partnership initiative between Nova Scotia Environment (NSE) and Nova Scotia Fisheries and Aquaculture (NSDFA) to inventory lakes throughout the province determining baseline water quality, in support of both sport fisheries and water resource management areas. The following weblink connects to a Nova Scotia Environment web map that includes the locations of the monitored lakes within the province and an alternative method for downloading the same lake chemistry dataset: http://nse.maps.arcgis.com/apps/webappviewer/index.html?id=7ded7a30bef44f848e8a4fc8672c89bd

All bank edges (of rivers, lakes, and wetlands), delimiter edges, glacier edges, and administrative boundary edges. These are the linear features that makeup the polygonal waterbodies

Water quality and ecosystem health data used to conduct a cumulative effects assessment of Canadian Great Lakes nearshore waters in support of the Great Lakes Water Quality Agreement are included in this dataset. The data was collected by various government and non-government agencies and organizations and integrated into this dataset to allow the assessment to be conducted. By conducting a regular, systematic assessment of cumulative effects in the nearshore waters of the Great Lakes Environment and Climate Change Canada (ECCC) is able to identify areas of high quality and areas under stress. Knowledge of ecological thresholds, other Great Lakes assessments, stressor information, indicators and local and traditional ecological knowledge will be used to aid in: 1) the identification and mapping of high quality nearshore areas and areas that are or may become subject to high stress and; 2) the determination of factors and cumulative effects that are causing stress or threats. Cumulative effects impacting the nearshore and future threats to areas of high ecological value will be better understood and the knowledge shared will assist in priority setting for science and management at a meaningful and practical spatial scale within each Great Lake and connecting channel.

All available bathymetry and related information for Twin Lakes 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.