Frost line depth in Adams County, WA
How deep the ground freezes in Adams County, WA
19 in. Dig to 19 in, just below the frost. Nearest NOAA station: Lind 3 Ne, 2.6 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.