Findings of Fact
The former Mazama Gap Filler Annex is located on the top of Slate Peak (elevation 7,440 feet) approximately 60 miles northwest of Okanogan, WA, and totals 118.93 acres. The property was developed as a radar station, including development of an access road, construction of a control building, installation of two 20,000-gallon underground fuel storage tanks, radar tower, sanitary latrine, and all associated improvements needed to operate the radar station. The unmanned annex was constructed in 1960 and supported the primary installation at Colville Air Force Station.

After less than a year in service, the annex was declared excess on 4 January, 1961, and a bid was accepted on October 23 for removal of security fencing, oil storage, and the control building. All salvageable materials, including the concrete building and underground fuel storage tanks, were removed from the site. The concrete building was reduced to the concrete slab, and the tower footings were left in place, as were the sanitary latrine, gravel roadway, sidewalks, and storm drainage.

The only visible remains of the radar installation are the concrete foundations for the radar tower and control building.