Annual run-off is predicted to decrease due to increased evaporation in large lakes. The possibility of heavy rain floods is expected to increase, especially in small river systems. The 74-km long Tohmajoki River discharges from Lake Tohmajarvi, and runs through the small, transboundary Lake Rameenjarvi and the small Russian Palkjarvi and Ruokojarvi lakes to Lake Ladoga in the Russian Federation.