Sheep Mountain Repeater Site, Alaska

Between Sawmill and Tahneta Pass, Sheep Mountain relayed communications for the Clear missile-warning network through Alaska's Glenn Highway corridor.

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Current Role: Former communications property in the Sheep Mountain area. Current operator, structures and ownership by parcel require review.

Sheep Mountain was an unattended two-way microwave relay on the White Alice Communications System's A Route. It connected Sawmill, 22 radio miles west, with Tahneta Pass, 12 radio miles east. The route carried communications for the Ballistic Missile Early Warning System (BMEWS) at Clear. Sheep Mountain was a communications station, not a radar station. ^{[1] [2]}

Role

Unattended, two-way TD-2 microwave repeater on White Alice's coastal A Route.

Direct links

Sawmill, 22 radio miles; Tahneta Pass, 12 radio miles.

Location

Near Glenn Highway mile 105-106. Alaska DEC records a later relay-property point at approximately 61.7883 N, 147.6751 W (NAD83).

Military period

The BMEWS relay group was built in 1960 and opened in 1960 or 1961; a precise Sheep Mountain commissioning date is not established.

The Clear Warning Route

The Air Force extended White Alice with two rearward communications paths for BMEWS at Clear. The coastal A Route ran through Southeast Alaska to an undersea cable connection, while the interior B Route ran through Canada. The Army Corps of Engineers dates construction of the TD-2 rearward stations to 1960 and their opening to 1960 or 1961. Sheep Mountain provided one of the shorter line-of-sight hops on the A Route. ^[1]

To the west, Sawmill connected with Neklasson Lake, a larger microwave and troposcatter switching station. To the east, Tahneta Pass passed traffic toward the Tolsona relay at Gulkana. Sheep Mountain preserved continuity between the adjacent microwave paths, allowing warning-related voice and data traffic to move over the larger network. ^{[1] [2]}

How the Microwave Relay Worked

The Air Force's 1983 history describes Sheep Mountain as an unattended, two-way microwave repeater near Glenn Highway milepost 106. The Corps describes the rearward-route station class as usually containing a radio-relay building, fuel storage and a TD-2 tower. Directional antennas received a signal from one neighboring station; equipment in the building passed it to the outgoing path. Unlike White Alice's long-range troposcatter stations, Sheep Mountain did not need the giant billboard antennas associated with those more distant links. ^{[1] [2]}

The photograph below shows a historic TD-2 tower at Soldotna, another White Alice microwave station. It illustrates the equipment class, not Sheep Mountain itself. The Rabbit Creek history has additional documented photographs of a TD-2 relay. ^{[1] [9]}

Army Communications Property

Sheep Mountain also had a documented Army Alaska Communications System repeater reservation. The Army sought land for the repeater south of Glenn Highway mile 105.5 in 1956. Public Land Order 2425 reserved approximately 287 acres in July 1961. Federal land records show that 75 acres in sections 29 and 32 passed by quitclaim deed in 1971 under the Alaska Communications Disposal Act. A 1974 order revoked the original reservation and identified roughly 212 acres under a separate public-interest withdrawal. ^{[4] [5] [10] [11]}

The Air Force's White Alice station list labels Sheep Mountain "Personal Property Only." The later AT&T Alascom repeater-property plan shows a tower, communications building, shop, power building and access road. It records how the relay property was arranged in a later period. ^{[2] [6]}

Commercial Transition and Later Site

RCA Alascom began operating White Alice under a system-wide lease in 1976. A federal notice that December listed a Sheep Mountain microwave application with links toward Sawmill and Tahneta Pass. RCA expressed interest in TD-2 microwave properties in 1977, and Sheep Mountain appeared in the 1978 Air Force appraisal program. The 1983 Air Force study still described an unattended two-way repeater. ^{[2] [7]}

Alaska DEC identifies a later AT&T Alascom Sheep Mountain Relay near Glenn Highway mile 105. Its record provides an approximate site point at 61.7883 N, 147.6751 W, associated with the later relay property. DEC issued a cleanup-complete decision with institutional controls in 2013 and recorded a further compliance review in 2024. ^[8]

Historical Significance

A Defense Department preservation inventory identifies "Sheep Mountain White Alice Communication System" as Alaska Heritage Resources Survey site ANC-00654. It found the site eligible for the National Register of Historic Places under Criteria A and G for its Cold War communications role. ^[3]

Chronology

• 1956 The Army's proposed Sheep Mountain repeater-site land withdrawal is published for a tract near Glenn Highway mile 105.5.
• 1960-1961 BMEWS rearward-route TD-2 stations, including Sheep Mountain, are constructed and opened.
• July 1961 Public Land Order 2425 reserves approximately 287 acres for the Army ACS Sheep Mountain Repeater Site.
• March 1971 A 75-acre portion of the Sheep Mountain ACS tract passes by quitclaim deed under the Alaska Communications Disposal Act.
• 1974 Public Land Order 5461 revokes the Army reservation and identifies approximately 212 acres remaining under a separate withdrawal.
• 1976 RCA Alascom begins operating White Alice under a system-wide lease.
• December 1976 A federal notice lists an RCA Sheep Mountain microwave application toward Sawmill and Tahneta Pass.
• 1978 Sheep Mountain appears in the Air Force's TD-2 property-appraisal program.
• 1983 An Air Force study describes the unattended Sheep Mountain repeater and marks it "Personal Property Only."
• 2013 Alaska DEC issues a cleanup-complete decision with institutional controls for the later relay property.
• 2015 A Defense Department inventory lists the Sheep Mountain White Alice resource as National Register eligible.
• 2024 Alaska DEC records a compliance review for the later relay property.

Information sources (11)

1. PDF[1] Historical Overview and Inventory: White Alice Communications System, U.S. Army Corps of Engineers (1988)

   Source for: BMEWS A Route, 1960-1961 development, TD-2 station class, Sheep Mountain's Sawmill and Tahneta Pass links and distances.

2. PDF[2] A Special Study of the Sale of the White Alice Communications System, U.S. Air Force (1983)

   Source for: unattended two-way repeater role, Glenn Highway milepost 106, "Personal Property Only" designation, RCA purchase interest and appraisal history.

3. PDF[3] Programmatic Approaches to the Management of Cold War Historic Properties, Department of Defense (2015)

   Source for: ANC-00654 identifier, National Register eligibility and 1961-1979 period of significance.

4. PDF[4] Public Land Order 2425, Federal Register, July 12, 1961

   Source for: Army ACS Sheep Mountain Repeater Site reservation and approximately 287-acre legal description.

5. PDF[5] Public Land Order 5461, Federal Register, December 27, 1974

   Source for: revocation of the Army Sheep Mountain land reservation, earlier quitclaim conveyance of a portion, and remaining approximately 212-acre withdrawal.

6. PDF[6] Attachment B, Figure 1.4, Sheep Mountain Repeater Site, Alaska Department of Environmental Conservation

   Source for: later relay-property building, tower and access-road arrangement; not a period White Alice as-built drawing.

7. PDF[7] Federal Register, December 13, 1976, RCA Alaska Communications microwave applications

   Source for: licensed Sheep Mountain links toward Sawmill and Tahneta Pass. The published longitude requires QA before being used as a map point.

8. WEB[8] AT&T Alascom Sheep Mountain Relay Site Report, Alaska Department of Environmental Conservation

   Source for: later relay name, approximate DEC location, cleanup status and 2024 institutional-control review.

9. WEB[9] Rabbit Creek White Alice Site, Radio Relay Station, Historic American Engineering Record, Library of Congress

   Source for: representative TD-2 station operation and period photographs, not Sheep Mountain photographs.

10. WEB[10] William F. McDowell Papers, University of Alaska Anchorage Archives and Special Collections

    Source for: cataloged Sheep Mountain Air Force real-property photographs in White Alice volume 5; not yet digitized.

11. PDF[11] Bill Ray White Alice Collection Finding Aid, Anchorage Museum

    Source for: cataloged 1957 Western Electric Sheep Mountain photographs.