The Selenga Pulp & Paper Company operates a zero discharge unbleached Kraft Mill. Located in an enviromnentally sensitive area, the operation is situated on the Selenga River, about 60 kilometers from the south shore of Lake Baikal. The Selenga River is the largest source of water for Lake Baikal, a lake considered by Russians as a natural resource jewel. Lake Baikal is one of the worlds deepest and cleanest lakes and contains one fifth of the worlds fresh water, more water than the Great Lakes combined. Until 1990, the Selenga Pulp & Paper Co. was considered one of the major polluters of the river. However, in August 1990, the mill began effluent recycling. This was accomplished by activated sludge technology in conjunction with chemical - physical treatment. The mill, in partnership with Sibgiprobum, a design institute for the Siberian pulp and paper industry developed the closed cycle system. The regulatory history, and treatment plant design will be reviewed in this paper.