Water quality and toxicity assessment in Koronia Lake - Greece

Lake Koronia, located in Northern Greece, is an environmentally sensitive a rea protected by Ramsar Convention. However, COD values higher than 900 mg/ l and nitrate-nitrogen concentration higher than 10 mg/l were measured in t he lake water. Furthermore, toxicity bioassays based on Daphnia magna, resu lted in mortality values of test species higher than 40% in the lake water. The poor water quality level has been attributed to the discharge of indus trial and domestic wastewater into the lake and to the negative water balan ce due to intense water pumping for various uses.