The site is a large reservoir on the Oued Inaouen, north-east of Fès, at 200 m altitude, flooded in 1973 by the construction of the Idriss Premier dam. The reservoir is 16 km long and mostly bordered by low, cultivated hills, although at the upstream end there is a small area of natural grassland. The average annual precipitation is 540 mm.
See Box for key species. Given the lack of natural vegetation around the majority of the site, its key interest is as a stopping point for Palearctic migrants. One species of the Mediterranean North Africa biome, Phoenicurus moussieri, occurs (see Table 2).
Non-bird biodiversity: The endemic fish Alosa alosa (DD) used to occur. Its current status in the reservoir is not known, and it may have been eliminated by introduced competitors and predators.
BirdLife International (2019) Important Bird Areas factsheet: Barrage Idriss Premier. Downloaded from http://www.birdlife.org on 06/12/2019.