Designed for individuals who have completed National Pollutant Discharge Elimination System (NPDES) level 1 laboratory training skills, this module provides waste water treatment plant operators with the basic skills and information needed to: (1) standardize a nephelometric turbidimeter; (2) determine the turbidity of a sample; and (3) calculate turbidity for tests requiring sample dilution. The instructor's manual contains a statement of instructional goals, lists of instructor/student activities and instructional materials, narrative of the slide/tape program used with the module, overhead transparency masters, and student worksheet (with answers). The student workbook contains objectives, prerequisite skills needed before the module is started, list of Environmental Protection Agency (EPA) approved nephelometric turbidimeters, sample problem, laboratory procedures for the nephelometric method of measuring turbidity, and worksheet. (Author/JN)