Shap Long Reservoir, Irrigation reservoir in New Territories, Hong Kong

Shap Long Reservoir, also called Chi Ma Wan Reservoir, is a man-made water body on Lantau Island surrounded by wooded hills and clear streams. Today it provides water for farming and serves as a fishing spot and hiking destination for visitors exploring the natural landscape.

Built in 1955, the reservoir held about 130,000 m³ behind a 91.1 m concrete dam and supplied Cheung Chau via a 6-inch submarine pipe to a fountain at the ferry pier. A 300 mm main from Silver Mine Bay in 1963 made it obsolete, and in the 1970s it became an irrigation reservoir.

The reservoir's name appears in two forms: Shap Long Reservoir and Chi Ma Wan Reservoir, after the peninsula it sits in. Its 1955 opening was marked by a water-spray ceremony at the Cheung Chau landing point, where a fountain was built to imitate the first cross-harbour submarine pipeline. The ceremony, planned for 27 August 1955, was moved to 3 September because the District Officer was ill.

The reservoir lies on Chi Ma Wan Peninsula, and both the Chi Ma Wan Country Trail and the Chi Ma Wan Mountain Bike Trail pass through it. From the bus stop at Pui O, follow Chi Ma Wan Road on foot for about an hour to reach the water. The paths cross woodland, so carry water and wear sturdy shoes.

The reservoir's clear, unpolluted tributaries have kept out invasive species, so it holds a large population of freshwater fish such as Oryzias curvinotus, the spotted ricefish. The surrounding mature woodland and tree-lined valley are what make this possible. The Chi Ma Wan Country Trail and the Chi Ma Wan Mountain Bike Trail both pass through the reservoir.