From Winthrop. Washington drive 14 miles west on Highway 20, turn right onto Lost River Road (county road #9140). Follow Lost River Road through Mazama to the end of the paved road at 7.5 miles. The road becomes gravel on Hart’s Pass forest service road 5400, 22 miles northwest of Winthrop. Travel about 0.25 mile, turn right into Monument Trailhead.