The 2017 Municipal Separate Storm Sewer System (MS4) General Permit regulation includes several mapping requirements. New and existing statewide data layers are compiled here to assist municipalities and institutions in complying with the permit requirements.
The CT MS4 Viewer includes data layers that are helpful in registering for and complying with the 2017 CT MS4 General Permit.
Layer Information |
Data Guide | Metadata | Download |
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CT 2012 Impervious Surface |
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Impervious: Impervious_2012* |
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CT 2020 Stormwater Impaired Waters (Rivers, Lakes, Estuaries) |
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MS4_layers: CT2020_Impaired_Rivers MS4_layers: CT2020_Impaired_Lakes MS4_layers: CT2020_Impaired_Estuary |
CT 2018 Stormwater Impaired Waters (Rivers, Lakes, Estuaries) |
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MS4_layers: CT2018_Impaired_Rivers MS4_layers: CT2018_Impaired_Lakes MS4_layers: CT2018_Impaired_Estuary |
CT 2016 Stormwater Impaired Waters |
MS4_layers: CT2016_Impaired_Rivers_V2 |
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CT DEEP Basins with 2012 Impervious Stats |
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MS4_layers: Impervious Cover by Watershed Basin |
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CT DEEP Basins (clipped to town boundaries) with 2012 Impervious Stats | - | ![]() |
MS4_layers: Impervious Cover by Watershed Basin (Clipped) | |
CT Towns with 2012 Impervious Stats |
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MS4_layers: Impervious Cover by Town |
CT MS4 Urbanized Area |
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MS4_layers: Urbanized Area |
CT MS4 Towns |
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MS4_layers: MS4 Towns |
*Impervious_2012 in is the Web Mercator Auxiliary Sphere Coordinate system while the Imperivous_2012_StatePlane service is in Connecticut State Plane NAD83 Feet. See the Coordinate Systems page for more information.