The Interim Enhanced Surface Water Treatment Rule establishes individual filter turbidity monitoring requirements for systems serving 10,000 or more people. If the turbidity in any filter exceeds 2.0 ntu for two consecutive months in two consecutive measurements taken 15 minutes apart, a comprehensive performance evaluation (CPE) is required. This requirement is intended to identify and correct poorly performing filtration plants. A CPE is the evaluation phase of the composite correction program (CCP). The CCP is a comprehensive, systematic process for identifying and correcting factors that limit the performance of a filtration plant. It was developed to improve plant performance by optimizing existing facilities, thus minimizing new capital construction. Includes 3 references, table, figure.