The objectives of this report are to describe the significance and impact of water quality impairment by coal mine drainage in the Clarion River basin, inventory the sources of coal mine drainage, by watershed, in terms of salient characteristics and quantity and quality of discharge, isolate and identify the principal polluting sources in each watershed unit studied, and outline essential steps in a mine drainage abatement program. Descriptions of the six inventoried watersheds of the Clarion River basin are contained in the following sections of this document. Each section contains its own summary and conclusions, maps, water quality data, and related mine drainage information.