The average discharge of the Mustajoki River is 0.8 m3/s and of the Karkisillanoja River 0.2 m3/s (determined by random measurements). The water level of Lake NuijamaanjSrvi is regulated in favor of waterborne traffic. It has definitive upper and lower levels of water and water level variation is narrow, with an annual fluctuation of some 20 cm during the year. The volume of water in the Saimaa Canal affects water flows in Lake Nuijamaanjarvi.