Ground Equipment Facility J - 33 Ground Equipment Facility J - 33 was a Federal Aviation Administration ( FAA ) radar station of the Joint Surveillance System ' s Western Air Defense Sector ( WADS ) with an Air Route Surveillance Radar ( ARSR - 4 ) . The facility was previously a USAF general surveillance radar station during the Cold War . History . The Cold War radar station near Mill Valley was one of twenty - eight stations approved by the United States Secretary of Defense on July 21 , 1950 , as part of the Permanent System radar network ( the Corps of Engineers managed construction for the USAF ) . Construction began at an upper location of the former World War II Mount Tamalpais Radar Site of the Aircraft Warning Service ( the WWII information center of the AWC was located at tbd for plotting radar tracks in the San Francisco area ) . Mount Tamalpais Air Force Station . Mount Tamalpais Air Force Station was the military installation where the 666th Aircraft Control and Warning Squadron was activated on January 1 , 1951 . The squadron " began operating a pair of AN / CPS - 6 B radars at this Bay - area site in late 1951 " . The Air Defense Command Manual Control Center at the station networked ground - controlled interception radars , and on March 10 , 1952 , the first Multiple Corridor System for identification of traffic arriving from overseas became operational outside San Francisco . Mount Tamalpais AFS was re named for the nearby Mill Valley community on December 1 , 1953 . Mill Valley Air Force Station . Mill Valley Air Force Station ' received an AN / FPS - 8 in 1955 ( subsequently converted to an AN / GPS - 3 ) , and during 1956 an AN / FPS - 4 height - finder radar operated ( superseded by an AN / FPS - 6 in 1958 . ) Mill Valley began operating an AN / FPS - 7 search radar in 1960 at facility built in 1959 by the General Electric company . During SAGE deployment , a Burroughs AN / FST - 2 Coordinate Data Transmitting Set ( CDTS ) was installed at Mill Valley AFS and " in late 1960 " began providing digitize radar tracks for telecommunication via microwave to the Air Defense Direction Center ( DC - 18 ) at Beale Air Force Base ( the squadron was re - designated 666th Radar Squadron ( SAGE ) on 15 January 1961 . ) By 1961 the 666th added AN / FPS - 6 and AN / FPS - 6B height - finder radars , and a detachment of the 666th began operating radars at the Mather AFB P - 58 radar station which , as with the Fort Ord P - 38A gap filler annex ( AN / FPS - 14 at ) , provided radar video to the Mill Valley CDTS for analog - to - digital conversion . NORAD Control Center . Mill Valley AFS was the " San Francisco Defense Area NORAD Control Center from 1961 to 1974 " after the Army ' s " 40th Artillery Brigade Air Defense Command Post " was established in September 1961 . Initially planned to use a Martin AN / MSG - 4 command , control , and coordination system ( instead deployed to 2 Alaska Nike / Hawk sites ) , Martin AN / GSG - 5 Battery Integration and Radar Display Equipment ( BIRDIE ) was instead emplaced the Project Nike " Master Direction Center " ( SF - 90DC ) . The AADCP operated by the 40th Artillery Brigade from 1959 until June 1971 ( 13th Air Defense Artillery Group from July 1971 to August 1974 ) received crosstelling from the Beale DC - 18 for coordinating fire from the TBD Nike batteries in the San Francisco Metropolitan Area . On July 31 , 1963 , Mill Valley P - 38 was redesignated as NORAD ID Z - 38 . With the inactivation of the San Francisco Air Defense Sector at Beale in 1963 , Mill Valley CDTS data was transmitted to Adair AFS , Oregon ( DC - 13 ) . GATR R - 18 was taken over by the 666th RADS as OL - A . In 1964 an AN / FPS - 26 A height - finder radar replaced the AN / FPS - 6 and the AN / FPS - 6B was modified to an AN / FPS - 90 . In 1966 the AN / FPS - 26A was converted to an AN / FSS - 7 SLBM detection & warning radar operated by the 3d Missile Warning Squadron and later as Detachment 3 14th Missile Warning Squadron on 8 July 1972 . After transfer to Air Defense , Tactical Air Command ( ADTAC ) on October 1 , 1979 , the 666th Radar Squadron was inactivated on September 30 , 1980 ( the SLBM radar deactivated c . 1980 ) . Most Mill Valley AFS property transferred to the NPS ( e . g . , for Mount Tamalpais State Park ) , and the radar facilities transferred to the FAA ( the USAF retained control of the height - finder that was modified to an AN / FPS - 116 ) . In 1995 the FAA operated an AN / FPS - 66A search set . In the late 1990s , the AN / FPS - 66A was replaced with an ARSR - 4 in the old AN / FPS - 26A / AN / FSS - 7 tower , the only CONUS site to place an ARSR - 4 in a tower other than a specially - designed ARSR - 4 tower . Ground Equipment Facility . On December 23 , 1980 , the USAF declared full operational capability for the 1st 7 Joint Surveillance System Regional Operations Control Center s , including the ROCC replacing the Mill Valley NCC . After 1980s turnover to the FAA , in " 1995 the FAA operated an AN / FPS - 66A search set " at J - 33 . In 2005 , the Federal Government ' s lease expired and the land was returned to the Marin Municipal Water District .