This photo was taken in 1987 using a film camera, may be the sky is not so blue now. To go there, you can take Green Minibus route 71 in Yuen Long Town near Yuen Long Estate, the street name is Taihang Street. After arrived Ho Pei Village, walk up the hill along a good concrete road, you can see the dam of the reservoir under the hill.
Or you can take bus number 51 above Tsuen Wan MTR station, alight in Lui Gong Tin, then walk about 1 hour to the reservoir. It is only a small reservoir but the scenery is good.