Frost line depth in Saguache County, CO
How deep the ground freezes in Saguache County, CO
39 in. Dig to 40 in, just below the frost. Nearest NOAA station: Saguache, 6.2 mi.
Your building department sets the legal frost line depth (IRC Table R301.2(1)); footings must go below it (R403.1.4.1). Call them before you dig.