sentences:  The largest individual pollution sources are the city of Varkaus and its pulp mills, although smaller settlements and diffuse pollution from agriculture and forestry contribute.The lake was heavily polluted by the pulp mills up to the 70s, but stricter regulation forced the mills to treat their wastewaters, and thus the lake recovered.The southernmost part of Haukivesi is Haapavesi, and most of its southern shoreline is covered by the city of Savonlinna.