1935: A 30-foot timber tower with L-4 cab. (Kresek)
June 17, 1965: "Summer engineering survey crews began work recently on the roads in the Payette National Forest. Crews are made up of college students and recent high school graduates. Surveyors are working on the road from Cuprum to Sheep Rock in the Hell's Canyon-Seven Devil's area of the forest. The 13-mile section of road will afford access to Horse Mountain Lookout and bids on construction will be offered early next spring." (The Idaho Free Press)
August 12, 1981: "With the cut back to only one lookout station, Horse Mountain, where Leonard Mooney commands a wide area view including Hells Canyon, the district has the services of a patrol plane out of McCall, which makes flights twice daily for a given number of days after each lightning storm." (The Adams County Record)
National Geodetic Survey
DESIGNATION - HORSE MTN LOOKOUT TOWER PID - RA1347 STATE/COUNTY- ID/ADAMS COUNTRY - US USGS QUAD - CUPRUM (1990)
DESCRIBED BY COAST AND GEODETIC SURVEY 1966 (CAA) STATION IS LOCATED ABOUT 2 MILES EAST OF THE SNAKE RIVER, 2 MILES NORTHEAST OF CUPRUM AND IS ON THE HIGHEST PART OF HORSE MOUNTAIN.
TO REACH FROM THE POST OFFICE IN CUPRUM, GO NORTHEAST ON A BLADED ROAD FOR 0.6 MILE TO A FORK AND SIGN LOCKWOOD SADDLE 5, TAKE THE LEFT FORK AND GO 4.8 MILES TO A SIDE ROAD LEFT IN A SADDLE AND SIGN HORSE MTN L.O. 1, TURN LEFT AND GO 1.4 MILES TO THE HIGHEST POINT AND THE STATION.
THE POINT INTERSECTED WAS THE TOP-CENTER OF THE LOOKOUT.