Wied ta’ Ghajn Rihana is a broad flat-floored valley located to the North of the Victoria Lines Fault and spans three local councils: Mgarr, Mosta and San Pawl il-Bahar. The valley system constitutes one continuous wied with two main tributaries—Wied ta’ Sejkla and Wied ta’ l-Arkata. Wied ta’ l-Imselliet and Wied tal-Hzejjen form the upper parts of the wied, joined by Wied ta’ Sejkla at il-Hzejjen. The valley then continues as Wied ta’ Ghajn Mula that is joined by Wied ta’ l-Arkata at Gnien Nixxuf. The downstream part of this valley, joining Wied il-Ghasel at Ghajn Rihana, is located on the opposite side of Triq Burmarrad and is locally referred to as Wied ta’ Ghajn Rihana.
Valley-sides and watercourses within valley systems present different environmental conditions that are exploited by distinct vegetation communities. Vegetation communities associated with valleys can thus be divided into those that characterise the valley-sides or valley-slopes and those that are associated with the watercourse. During the winter months the watercourse of Wied ta’ Ghajn Rihana holds a substantial amount of freshwater, supporting biotic communities that are typical of local watercourses.
The valley banks support limited stretches of deciduous trees that are generally associated with watercourses (riparian woodlands) and are quite rare within the Maltese Islands.
MEPA scheduled Ghajn Rihana valley system as an Area of Ecological Importance and Site of Scientific Importance as per Government Notice No. 226/06 in the Government Gazette dated 10 March 2006.