Built by Eben S. Coe (on behalf of owner David
Pingree) in the 1850s, Lock Dam was designed to allow the
transfer of logs from the area around Eagle and Churchill
Lakes down into the Penobscot River Basin by adjusting the
water levels in the locks and floating groups of logs from
Eagle Lake over to Chamberlain. From there, they could be
driven downstream to Telos Lake and through the
Telos Cut. This process greatly expanded the acreage of
timber that could be brought down to Bangor mills and markets,
but the slow rate of the lock process limited the number of
logs that could move through in a given period of time. By
1906, Lock Dam was abandoned as a log moving method in favor
of the mechanically powered Tramway.
Lock Dam was originally a timber crib dam. It is no longer that type and had not been for many years prior to the establishment of the Allagash Wilderness Waterway in 1966. The original timber crib structure on Chamberlain Lake, built as one of two dams providing a lock between Chamberlain and Eagle Lakes, had deteriorated, collapsed, and was buried under an earthen dike before the Waterway was established in 1966. Since that time, Lock Dam on Chamberlain Lake has been an earthen embankment with sections of parapet wall that consists of embedded vertical spruce planking or logs and a promontory lined with a corrugated steel bulkhead and riprap extending 3-5 feet above lake level. A 3 diameter, gated culvert spillway, which predates the Waterway, allows discharge of water into Allagash Stream below Lock Dam and provides water for canoeing to Eagle Lake. No vestiges of the second lock dam at Eagle Lake remain.
DPPL acquired Lock Dam along with Telos Dam and their associated structures in 2000 in order to continue management of water levels consistent with the Waterways management objectives and to prevent changed or expanded private use of the associated buildings in a manner inconsistent with the Waterways management objectives. The dams are maintained and managed by DPPL as part of the Waterway. DPPL has no plans for these dams, except to improve their condition and maintain them, nor does DPPL intend to change the flow regimes from those currently in effect.
"As it looked from the twenties thru the mid-forties. Then the roofs came down over the walkways - with the roof over the gates lasting quite a few more years!" -- interpretive panel from a few decades ago.