Gefersa reservoir is 18 km west of Addis Ababa (by road) in West Shewa Zone. Although within Oromiya Region, Addis Ababa Water and Sewage Authority have administrative control of the area. The reservoir is in a shallow basin about 10 km wide, stretching between the Wechacha and Entoto mountains. The Gefersa river and its feeder streams are part of the Akaki river catchment. The reservoir formed behind a main dam built in 1938 (and modified in 1954) and a second, smaller dam, built in 1966, upstream from the main dam; the water-storage capacities are c.6,500,000 m3 and c.1,500,000 m3 respectively, and the two dams control a catchment area of c.5,700 ha. The reservoirs supply treated water to Addis Ababa. The reservoirs themselves are virtually free of large aquatic plants, probably due to the constantly fluctuating water-level. Patches of sedge occur where permanent streams flow into the reservoirs, and on the western and southern sides of the main reservoir, long, shallow valleys with small streams support swampy vegetation. The area immediately around the dam and on the northern side of the reservoir is enclosed and supports well-established exotic trees of Eucalyptus globulus, Cupressus lusitanica, Pinus patula and P. sylvestris. Meadows in this enclosure have been protected from grazing for many years and have developed a flora quite different from the heavily used areas outside. Much of the area surrounding the reservoirs has been closely planted with Eucalyptus, although there are some patches of small trees, e.g. Maesa lanceolata, Buddleja polystachya and Maytenus obscura, the climbers Clematis simensis and Jasminum abyssinicum and also bushes of Rosa abyssinica. All other areas are densely inhabited and farmed. The valley bottoms are used as pastureland that floods in the rainy season, while the higher slopes are cultivated, with barley and wheat the main crops, and smaller areas of pulses (field pea and faba bean) and oil crops (niger seed and linseed).
See Box and Table 3 for key species. Sarothrura ayresi occurred before the swamp was developed into a reservoir, but it almost certainly no longer does so. Rougetius rougetii is present in small numbers, however. The edges of the reservoir form a good habitat and suitable feeding ground for a sizable population of Cyanochen cyanopterus. Away from the water, grassland species such as Macronyx flavicollis can be seen (in small numbers), and Serinus nigriceps often occurs. The woodland around the reservoir supports a further range of Afrotropical Highlands biome species. A good variety of Palearctic and Afro-tropical ducks and geese occur at Gefersa, the most common Afrotropical species being Cyanochen cyanopterus (maximum monthly average, August, 154).
Non-bird biodiversity: None known to BirdLife International.
Pressure/threats to key biodiversity
The site supplies the water needs of Addis Ababa and is officially protected by Addis Ababa Water and Sewage Authority. In the past, the main reservoir was completely enclosed by a wire fence, with people and domestic animals forbidden to enter. However, farmers in the surrounding area felt they had been deprived of water-use and grazing rights, and now herds of domestic animals graze around the reservoir. Agricultural activities on a small scale are also seen in the area. Both grazing and cultivation around the reservoir are a health hazard, and therefore undesirable. The farmers greatly resent geese and ducks, which come to their fields and feed on cereal crops. The high rate of siltation is a major long-term problem for the reservoir, as it severely affects the capacity of the reservoirs and results in a shortage of usable water for Addis Ababa. Effective erosion control would have to be implemented throughout the catchment area. The Eucalyptus globulus plantations are also a problem: the species is well known to deplete soil and groundwater by absorbing it with its wide lateral and deep vertical roots.
BirdLife International (2022) Important Bird Areas factsheet: Gefersa reservoir. Downloaded from
http://www.birdlife.org on 13/08/2022.