A biological survey of Rankin Lake provided no evidence that discharge from a sewage lagoon located at Camp Wakana was affecting the lake. The practice of not allowing any discharge from this lagoon during the summer months should be continued. Since any malfunction of the treatment system presents a potential hazard for Rankin Lake, regular inspection of the lagoon should be continued. The number of cottages on the lake, many of which utilize septic field systems for sewage disposal, necessitates regular sampling for bacterial contamination. Particular emphasis should be placed on securing bacteriological analyses during the summer months. Snails present in some areas of the lake were found to harbour the tiny parasite which is responsible for swimmers' itch. Should the cottagers decide that chemical control of snails is essential to combat the problem, a survey will be necessary to delineate the areas which require treatment. Because of the potential hazard to fish and fish food organisms, it will be necessary that approval be secured from the Ontario Department of Lands and Forests and that a permit be issued by the Ontario Water Resources Commission prior to any chemical application.