Location of marker is approximate, but the dam was nearby. It is shown on maps 1901, 1924.2, and 1913.1 at https://www.hkmaps.hk/viewer.html
It was built to supply water to the new Mint at East Point. The initial tender for its construction appeared as Government Notification 13 in the Gazette for 21 Jan 1865:
In the second half of 1928, there was only 58 mm of rainfall and from January to mid-July in 1929, only another 40 mm of rainfall was recorded (between October 1924 and March 1929, there was almost no rainfall at all). Despite all the reservoirs being full in the summer of 1928, the lack of rain led to a dramatic fall in water levels. The beginning of the wet season in April 1929 did not bring the desired precipitation. All reservoirs on Hong Kong Island except Tai Tam Tuk dried up.
From the very beginning of the colony, the supply of fresh water always was a challenge. The increasing population needed more and more fresh water to be supplied continuously throughout the whole year. This was achieved by the construction of dams and conduits (e.g. Pokfulam and Tai Tam in the 19th century), but it always was a chase between increasing population and increasing storage capacities. The whole system depended on sufficient rainfall. In some years, this did not work because rainfall quantities were too low.
I've got another 'old Hong Kong waterworks' puzzle for this week's newsletter. Unlike the recent pouring pipe mystery, this one took much longer to solve. It all started around ten years ago, back in a time of tadpoles.
Looking for tadpoles, finding pillars
This tunnel was part of the first section (phase) of the Shing Mun Valley Scheme. It is marked (I) on the map below.
This tunnel was part of the first section (phase) of the Shing Mun Valley Scheme. It is marked (H) on the map below, connecting the South Conduit (G) to the Reception Reservoir (I).
The conduit was part of the first section (phase) of the Shing Mun Valley Scheme. It is marked (G) on the map below, connecting the North Tunnel (F) to the South Tunnel (H).
Part of the first section (phase) of the Shing Mun Valley Scheme.
It was completed in late 1925, and is described in item 224.d of the PWD's Annual Report for 1925:
(d). North Conduit.—A Contract for $70,801.00 was let in February to Mr. Ng Wah who made excellent progress and completed the works by the end of the year. It commences at the termination of the Temporary Conduit in the Gorge below Pineapple Pass and discharges into the North Tunnel below Smuggler’s Ridge.
This tunnel was part of the first section (phase) of the Shing Mun Valley Scheme. It is marked (F) on the map below, connecting the North Conduit (E) to the South Conduit (G).
The completion of the project is mentioned in item 47.iv of the PWD's Annual report for 1897. I've highlighted the comment about the "roof formed of brick arching", which suggests it is similar in style to the service reservoir at Bishop's Hill, unless it has been rebuilt at some point.