Site description A reservoir constructed during 1990 and 1991 by damming a tributary of the Ngotwane river just south of the village of Bokaa, less than 20 km north of Gaborone. The body of open water stretches for some 6 km or more and is over 500 m wide at its maximum; it has a north-west side-arm where the Kopong tributary joins the watercourse formed by the Metsemotinaba, Gakgatia and Gamoleele and other tributaries. The dam is surrounded by Acacia savanna, which is used for grazing by many sheep, goats, donkeys and cattle, and away from the reservoir there are some cultivated areas. Some sections of the shore are open bare mud but there are patches of Cyperus, Phragmites and other emergent aquatic vegetation although this is rather sparse and degraded because of pressure from domestic stock. Although the reservoir has a perimeter fence this is broken in several places so stock have access to much of the reservoir edge. One point on the southern shore is used as a picnic site by weekend visitors. The west side of the north-west arm of the reservoir is fringed by taller trees which support a large mixed heronry.
Key Biodiversity See Box for key species. Bokaa Dam occasionally supports small numbers of Pelecanus rufescens. Waterfowl counts between 1991 and 1995 reached a maximum of c.4,000 birds. The only species present in numbers exceeding the 0.5% threshold are Podiceps cristatus (max. 46) and Netta erythrophthalma, numbers of the latter having built up since 1994, usually peaking during the August–October period.
Non-bird biodiversity: None known to BirdLife International.