Michigan Great Lakes Grids: Michigan
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- Michigan Department of Natural Resources
- In the Great Lakes, grid systems defined by latitude and longitude minutes have been used for a number of decades as a fishery standard for data reporting. The Michigan Department of Natural Resources (MDNR) Fisheries Division created this GIS layer in 2019 to depict the MDNR Michigan Great Lakes grid (v3.2) standard for Fisheries Division applications for the waters of the State of Michigan, and for Canadian waters in the St. Clair Detroit River System (SCDRS), as of June 2019. This GIS layer was created by incorporating grid boundaries and ID values from a number of existing grid standards. This layer is a composite grid that incorporates grid boundaries and ID values from the following GIS data standards for different areas of the Great Lakes: 1) 10-minute grids for Lakes Huron, Michigan, Superior and the St. Mary's River came from the Institute for Fisheries Research (IFR) version 1 (v1) of the 10-minute grids. 2) 10-minute grids for Lake Erie came from version 2 of the IFR 10-minute grids created by the Great Lakes GIS (GLGIS) project, and 3) 5-minute grids for SCDRS came from 5-minute grids developed by the GLGIS project. Version 1 of the IFR 10-minute grids were created in 1998, and only covered the water bodies listed above (Lakes Huron, Michigan, and Superior, and the St. Mary's River). This is the GIS dataset that was used as the grid standard for the 2000 consent decree. The grid boundaries and ID values in v1 were originally based off paper maps, but the publication source of the paper maps is unknown. In v1, 10-minute grids do not always have rectangular boundaries where each side represents 10-minutes of latitude and longitude, especially near the shoreline. In order to create the v3.2 composite layer, some features in the v1 GIS dataset that were missing ID values were assigned ID values based on historical creel maps or nearby grid ID values. Version 2 of the IFR 10-minute grids was created in 2006 and provides coverage forall five Great Lakes, but only partial coverage in the connecting channels, with no coverage in SCDRS. In contrast to v1, 10-minute grids in this dataset are true 10-minute grids with rectangular sides that strictly follow 10-minute latitude and longitude lines (along with some cases where two true 10-minute grids were combined into one grid cell with one ID value). Due to the differences in grid boundaries, there are some different ID values across v1 and v2. The GLGIS 5-minute grid GIS dataset was created in 2006 at IFR. This layer contains rectangular 5-minute grids that are true 5-minute grids, with each side of every grid representing 5-minutes of latitude or longitude. 5-minute grids were used for SCDRS in v3.2 to align with historical data reporting standards in the region, and because there are no 10-minute grids that fully cover SCDRS. 5-minute grids created by the GLGIS only exist for SCDRS, Lake Erie, and Lake Huron, and the reason for this is unknown. SCDRS grids on the Canadian side of the basin are included in v3.2 for Fisheries Division data reporting needs that may include Canadian areas of SCDRS, but these grids in Canadian waters may not represent the standard that is actively used by Canadian agencies. In order to create the v3.2 composite, grid cells from the various GIS data sources were merged together for water bodies as specified above. In v3.2 the grids are almost exactly as they appear in the source data (with minor edits such as edge matching) except where 10-minute grids 602 and 603 in Lake Erie from Version 2 were replaced with GLGIS 5-minute grids. These grids cover the transition between the Detroit River and Lake Erie, where 10-minute grids are too large for some fisheries data reporting purposes. Therefore in v3.2, the two 10-minute grids were replaced with four 5-minute grids from the GLGIS 5-minute grid dataset. ID values were kept from the 5-minute grids for the two northern cells but thetwo southern grids cells retain ID values from the GLGIS v2 10-minute grids (602 and 603). This was done to allow continuity with historical data that has been recorded for 10-minute grids 602 and 603, but users need to be aware that these ID values in v3.2 are now associated with 5-minute grids instead of 10-minute grids.GIS layer was last updated 8/14/2018. Metadata last updated 6/25/2019.
- Resource Class:
- Datasets and Web services
- Resource Type:
- Vector data
- ISO Topic Category:
- Inland Waters
- Date Published:
- Temporal Coverage:
- Michigan DNR Open Data Portal
- The access links for this item were reported broken. It may have been retired from its source data portal.