Gophers are active in the winter, burrowing under the snow to find food and lining the burrow with earth or duff. When spring comes this burrow collapses, leaving a linear mound called a burrow cast. See below for examples of burrows and winter burrow casts.
The pocket gopher is seldom seen above ground and usually plugs the holes of active burrows.
The most obvious sign is the burrow casts left as the snow melts. Klammath Falls, OR Juanita Lake, CA Lolo Pass, Mt Hood, OR Sometimes burrow is just below the surface of the ground leaving an open run.
The width is about 2" while the mounds are about 2.5". Boulder Lake, Mt Hood, OR The gopher will often plug his active summer burrows, probably to keep out predators. Burrows