Solved! Go to Solution.
Hi Joshua,
You can accomplish this using the Reclassify tool in Spatial or 3D Analyst toolbox. Open the tool, select your DEM for the input, and then click 'Classify'. Set the classes to 3 and click OK. Specify one of the 'Old Values' range to your desired elevation range that you want the polygon to be. For example, if your DEM has values from 1.5 - 58.7, and you're interested in values 20-30, then you should specify the Old Values to be in ranges:
0 - 19.9
20.0 - 30.0
30.1 - 58.7
The new values would default to 1, 2, and 3. After your new raster is created, you can open the attribute table and select Values = 2. Next run the Raster to Polygon tool on the selection and you will have your new polygon.