For applicable areas, Chapter 14.51 of the Dane County Code of Ordinances requires that thermal control practices be included in a stormwater management plan if a development is within a thermally sensitive area, e.g. a watershed of a river or stream identified as an existing or proposed cold water community. This is to ensure no increase in temperature of stormwater post-construction in order to protect cold water communities. See the metadata for cold water communities and the web locator for thermally sensitive areas for additional information (<http://www.co.dane.wi.us/landconservation/cws/index3.html>).
The layer was created by the former Dane County Land Conservation Department (now a Division in the Land & Water Resources Department) with data from the Wisconsin Department of Natural Resources (WDNR) and the University of Wisconsin-Madison Land Information and Computer Graphics Facility (LICGF).
The attribute "tharea" was added and coded as a 1 for thermally sensitive areas; all other areas were coded as a 9. The coverage was then converted to a shapefile.
In 2008, all polygons in the Towns of Vermont, Blue Mounds and Perry (per request from WDNR) were coded as 1. This changed the attribute value from 9 to 1 for four polygons -- these areas are draining to cold water communities outside of Dane County.