Abstract
Water chemistry and algal vegetation of five reservoirs in south-western Saudi Arabia were surveyed in August 1991. The waters were slightly alkaline with varying levels of nutrients. Inorganic nitrogen concentrations were high at all sites. The ratio of monovalent to divalent cations was not especially high. Micronutrient levels were high at certain locations. Green algae were found at all sites and dominated by the three orders Chlorococcales, Cladophorales and Zygnematales. Blue-green algae were found at all but one site; certain species were restricted to a particular location.