A water quality study was undertaken during the summer of 1990 in the nearshore area along the Lake Huron shoreline between Canatara Beach and Brights Grove. The purpose of the study was to determine possible sources of bacterial contamination which were responsible for numerous beach closures in 1989. This study was undertaken at the request of the Abatement Section, Sarnia District office, who have received queries from the Lambton County Health Unit, Municipal Officials and the local media as to the sources of the bacterial contamination. The study was designed to investigate potential sources such as municipal storm drains, septic tank systems (direct/indirect discharges), the seasonal lagoon discharge from Brights Grove and agricultural runoff inputs. Sampling locations were established at various access points along the 14 kilometres of shoreline between Canatara Beach and Brights Grove. Two surface water tributaries flow into Lake Huron within this reach; Pulse Creek and Perch Creek. Perch Creek receives the seasonal discharge from the Brights Grove lagoons. The entire area is used for water use activities including swimming, boating and wind surfing. Two main beaches are the Canatara and the Brights Grove beaches. Owing to restricted access along this reach, smaller public beach areas exist at public access points such as at the ends of major roads (Murphy, Modeland, etc.).