Water Quality Assessment of Large Alpine Sevan Lake

Lake Sevan is one of the largest high-altitude freshwater lakes in Eurasia and Armenia's largest reservoir. A 20 m drop in the Sevan level has led to intense eutrophication of the lake. Accordingly, raising the water level by the planned 6 m is considered a radical measure to preserve the lake's ecosystem. The main goal of this research was to develop a system of water quality indices as an important component of science-based management of lake Sevan water resources. The problem was solved using a quantitative modification of the expert panel method (Delphi). A set of state variables was selected and a procedure was developed for converting environmental values of state variables into qualitative (rating) values; the assessment was done of the desired reference state, and the water quality index (SWQI) was calculated. The application of the developed system for assessing the water quality of lake Sevan made it possible to quantify the trend of improving water quality in recent years and to identify the significant relationship of SWQI with the water level and epilimnetic water temperature.HighlightsA system of indicators of water quality is developed.The reference state for the lake is established.Using SWQI water quality is assessed.The relationship between SWQI and potential threats is discussed.