Kranji Reservoir and Estuary
Location:
 1°25'N, 103°43'E; at the northwest corner of Singapore Island.
Area:
c.80 ha.
Altitude
 0-5m.
Biogeographical Province:
4.7.1
Wetland type:
 02, 06, 07 & 17
Description of site:
 A former river which has been dammed at its mouth to form a freshwater storage reservoir. There is still a small estuary with mudflats and very degraded mangroves below the dam. The most important area is the flooded edge of the reservoir which forms a freshwater marsh, a fairly rare type of habitat in Singapore and Peninsular Malaysia. The reservoir is fed by run-off from the catchment area, and probably does not exceed 10m in depth. The maximum tidal range on the mudflats is 3.2m.
Climatic conditions:
 Humid tropical climate with an average annual rainfall of 2,373 mm, an average relative humidity of 85%, and temperatures ranging from 23.7 to 30.7°C.
Principal vegetation:
 Coastal mangroves with species of Avicennia and Rhizophora in the estuary;
grassland with Imperala cylindrica and Panicum maximum, remnants of Achrostichum and some Acacia trees on the edge of the reservoir; extensive growths of Eichhornia crassipes at certain times. Urban areas, old coconut estates, vegetable farms and secondary growth nearby.
Land tenure:
 Most of the area is owned by the Public Utilities Board (Water Department); the
surrounding areas are Government land.
Conservation measures taken:
 The reservoir is covered under the legislation which prevents pollution of a public water supply.
Conservation measures proposed:
 A recent proposal by the Malayan Nature Society (Singapore Branch) that steps be taken to re-establish the freshwater marshes as a Nature Reserve, replacing the one which was degazetted some years ago, has been rejected by the Public Utilities Board on the grounds that the existence of any marshy areas at the reservoir conflicts with their aim of having a "neat" reservoir. The Malayan Nature Society has subsequently proposed that the mangrove belt and muddy foreshore on the seaward side of the dam be developed as a Nature Reserve.
Land use:
 Public water supply; industry, farming and parkland in the surrounding areas.
Possible changes in land use:
 In the future the marshland area may be reclaimed to prevent the development of the Eichhornia beds. The surrounding areas will undoubtedly be used for industry or housing purposes, although this will not be allowed to reduce water quality as it is a public water supply.
Disturbances and threats: Possible land-fill, and possible "neatening" of the edges of the reservoir in an attempt to improve water quality.
Economic and social values: The site is a public water supply. The reservoir supports a freshwater fishery which is
exploited on a limited and controlled scale. Sport fishing is allowed along one stretch of the bank (one of the few such sites in Singapore). Public recreation areas are provided along the dam and people collect shellfish on the mudflats, although the latter is mainly for pleasure rather than commercial purposes. The Singapore Science Centre has used part of the dam area for school science projects. There is a very good potential for converting the marsh area into a public recreation area to provide education facilities on freshwater systems and especially on the birdlife found there.
Fauna:

Several species of fish occur, including the Climbing Perch. It is unlikely that there are any rare species, although there has not been any serious study of the area.The area is noted for its waterfowl. It has the only breeding colonies of Ardea purpurea (over 100 individuals) and A. cinerea in Singapore. These are the only known breeding colonies of these species south of Selangor in Peninsular Malaysia. The marshes are particularly rich in Rallidae; Rallus striatus, Porzana fusca, P. cinerea and Amaurornis phoenicurus are common, and there are large numbers of Gallicrex cinerea (100+), Gallinula chioropus (200+) and Porphyrio porphyrio (200+), species seldom seen elsewhere in Singapore. Ixobrychus sinensis is a very common winter visitor, and has recently begun to breed. I.eurythmus and Hydrophasianus chirurgus are rare visitors. The grasslands hold probably the largest Singapore population of Ixobrychus cinnamomeus, and are important wintering areas for Acrocephalus orientalis, A. bistrigiceps and other small passerines. The largest congregations of the weaver Ploceus philippinus in Singapore nest in the nearby coconuts and feed on the grass seeds.

The offshore mudflats can provide low-tide feeding for up to 2,000 shorebirds, adding greatly to the overall diversity of the site. The most numerous species are Pluvialis dominica, Charadrius mongolus, Tringa totanus, T. nebularia and Calidris ferruginea. Chlidonias leucoptera and Sterna albifrons feed over the sea and the reservoir in large numbers (500+ of each).

Some of the largest Water Monitors Varanus salvator in Singapore are to be found here.
Special floral values: None known.
References: Hails (1985 & 1987b); Hails & Jarvis (1987).
Criteria for inclusion:
 2b, 3b.
Source: Christopher J. Hails.