Half Moon Bay Radar L-82 (site) (Half Moon Bay, California)

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Also known as VHF 4K5 Half Moon Bay.

On 10 April 1942, the War Department authorized the acquisition of land for use as an antiaircraft radar site. It was initially established under the Western Defense Command and Fourth Army and was known as the Half Moon Bay Tactical Position, Harbor Defenses of San Francisco. With radar being so secret, it was common to give the various sites description that masked their true mission. Sites were called "listening posts" or "tactical positions". Sites were also constructed to resemble farm buildings common to the coastal regions of California to further hide their true purpose. This deception continued throughout World War II to the point that the USACE report, War Department Owned, Leased and Sponsored Facilities, 31 December 1945, still referred to the Site as part of the Harbor Defenses of San Francisco and was not shown on any of the Army of the United States Station Lists published by the Adjutant General of the U.S. Army as late as 7 May 1946.

The ste was divided into two functional areas. The primary mission of the ste was the operation of a radar station known as L-82 and was located in the northern portion of the reservation. The secondary function was to operate a VHF Direction Finder station in the southern portion of the reservation called 4K5. Although manned by two separate detachments, some support functions, such as perimeter defense, were shared.

On 24 July 1947, the southern portion of the reservation that that was made up of several leased parcels was declared surplus to the needs of the Army Air Forces. With that, the Direction Finding Station 4K5 was deactivated and its equipment sent to Berkeley, California.

On 2 January 1948, the headquarters of the 636th AC&W Squadron moved from Hamilton Air Force Base to Half Moon Bay. The squadron conducted joint training with the Hamilton Air Force Base's 325th Fighter Group and oversaw dismantling of radar stations Olema, Gualala and Carmel, California. The History of the 505th AC&W Group, 1 July-31 December 1947 reported that AN/CPS-1, SCR-588-B, TPS-10 and AN/CPA-7 radar sets were present at Half Moon Bay as well as several power units.

In October 1951, Mill Valley Air Force Station (Site P-38/Z-38) atop Mount Tamalpais became operational, replacing the Lashup site at Half Moon Bay. that time the U.S. Air Force declared the Site as surplus and turned over the 3 remaining tracts of land to the USACE for disposal. The three leases were terminated on 31 May, 30 June, and 28 October of 1952.

www.corpsfuds.org/reports/INPR/J09CA0821inpr.pdf www.militarymuseum.org/HMBAWSS.html