The site is the second-largest man-made reservoir in Morocco, on the Oued Oum Er-Ribi’a, located approximately 50 km south of Settat. Lying at an altitude of 265 m, the reservoir is around 30 km long, has a surface area of 14,000 ha, and a maximum depth of 60 m. Situated in a hilly valley, the reservoir’s border is heavily indented and there are many islets, some of which only emerge when the water-level is low. The reservoir’s shores are mainly rocky, and are partly wooded with Eucalyptus and Acacia species. Aquatic plants such as algae and Potamogeton grow in profusion along a 10–50-m-wide strip around the reservoir’s edge. When the water-level drops, exposed mudbanks and the drying aquatic plants provide extensive feeding habitat for waterbirds. Average annual precipitation is 200 mm.
See Box for key species. The Barrage al Massira regularly harbours large numbers of wintering waders and waterfowl: 42,000 birds were counted in January 1993 and 55,000 in January 1995, of more than 30 different species. Marmaronetta angustirostris is a regular wintering visitor; 1,973 were recorded in January 1993 and 280 in January 1995. In addition to those listed below, maxima of 7,000 Anas penelope, 4,000 Aythya ferina and 20,000 Fulica atra have been noted. Around 20 waterbird species are summer/breeding visitors, mainly breeding on the islets in the reservoir. It is suspected that Fulica cristata may also approach threshold levels, but no data are available.
Non-bird biodiversity: None known to BirdLife International
BirdLife International (2019) Important Bird Areas factsheet: Barrage al Massira. Downloaded from http://www.birdlife.org on 11/12/2019.