The water level of Lake Mälaren has been regulated since the 1940?s. A recentinvestigation suggests that the current regulation needs to be adjusted in order toprevent a decline in water level, salt water from infiltrating from Lake Saltsjön,and risk of floodings. In addition to these preventions, the new regulation couldpotentially effect the natural environment and agriculture practices in the lowlands that surround the lake. The new regulation proposal calls for an increase invariations in Mälaren?s water level during seasons, while the annual mean waterlevel will remain the same.