Lake Zeway is a slightly alkaline lake in the central section of the Ethiopian Great Rift Valley. It lies to the east of Zeway town, c.115 km south-west of the East Shewa Zone capital, Nazaret. It is within a broad, down-faulted basin that to the south, and within the same drainage, includes Lakes Abijatta, Langano and Shalla. Also to the south, the landscape is dominated by Mt Aleltu (c.1,880 m). Within 10 km to the east and west of the lake are higher faulted ridges. To the north, the land rises gently to 1,670 m where it meets the watershed of the Awash river and Koka dam reservoir. The lake is c.29 km long and 20 km wide, with a maximum depth of 8 m (mean c.2.5 m), and a seasonal variance of 0.5–1.2 m. There are several islands, some inhabited, the largest probably for 1,000 years and supporting an Orthodox Christian community. The Lake Zeway catchment is 7,025 km², fed by a number of rivers, of which the Meki and Catar are most significant. The Meki drains the Gurage mountains to the west and north-west of the lake, and the Catar rises in the Arsi highlands to the east. Lake Zeway drains into Lake Abijatta via the Bulbula river. Lake Zeway is for the most part bordered by swamp: discontinuous blocks of Typha spp. and Cyperus papyrus fringe the shoreline, the latter being used to build boats similar to those found in Lake Tana. However, much of the shoreline and open water has now been invaded by Eicchornia crassipes. Narrow thickets of Aeschynomene elaphroxylon (which provides a light balsa wood used to build boats) are found in areas subject to flooding and along the banks of the Bulbula river. Immediately inland, and especially along the western shoreline, there are expanses of Cynodon plectstachyus and the endemic C. aethiopicus which provide valuable grazing when the lake is low. However, where there is alkaline seepage, vegetation cover may be sparse and largely confined to low tussocks of the unpalatable grass Sporobolus spicatus. Most of the area around Lake Zeway used to be covered in Acacia woodland, although much of this has now been cleared for farmland, especially large-scale irrigated fields producing export crops and cut flowers. Lake Zeway has a thriving, traditional fishing industry utilizing small boats, nets and lines. The main market for the catch is Addis Ababa.
See Box for key species. Lake Zeway may support over 20,000 waterbirds on a seasonal basis. The most common species are Pelecanus onocrotalus, Leptoptilos crumeniferus (which roosts in large numbers by the lake, adjacent to town), Dendrocygna bicolor, D. viduata, Larus ridibundus, L. cirrocephalus, Chlidonias hybridus and C. leucopterus. There is also a mixed roost of several thousand Phalacrocorax carbo and P. africanus close to the fisheries jetty. Other interesting species include Thalassornis leuconotus, Nettapus auritus and Gallinula angulata (in small numbers), Sterna caspia and S. sandvicensis (isolated records only) and Phalaropus lobatus. Large numbers of Hirundo rustica and Motacilla flava have been seen close by and may roost at the site.
Non-bird biodiversity: Eight species of fish are known, one of which, a barbel Barbus zwaicus, is probably endemic.
Pressure/threats to key biodiversity
The town of Zeway is expanding rapidly as it develops into a major transport and marketing centre. All the water for the town comes from the lake. The expansion of irrigated, intensive agriculture (producing fruit, vegetables and cut flowers) has introduced chemical fertilizers and pesticides into the ecosystem, and a decline in waterbirds and large fish has been noted in recent years. The recent invasion of Eicchornia crassipes is undoubtedly having an adverse effect on the breeding grounds of the fish. Increasing demands are being made on the water and other natural resources of Lake Zeway: Typha spp. and Cyperus papyrus are cut (and sold) for thatching houses; birds are caught to sell, and tourists shoot some for sport. Increasing numbers of people use the lake for recreational purposes causing disturbance to feeding and roosting birds. Goats were recently introduced to Gelila and Debre Sina islands, seriously affecting the native trees and grasses.
BirdLife International (2022) Important Bird Areas factsheet: Lake Zeway. Downloaded from
http://www.birdlife.org on 04/10/2022.