Statutory provisions under the 1986 amendments to the Safe Drinking Water Act require water utilities using unfiltered surface sources to disinfect and filter or to meet stringent criteria for remaining unfiltered. Three unfiltered surface water systems in Oregon were evaluated in two areas: their ability to meet the criteria for remaining unfiltered and the steps they must take to document the shortcomings of their systems and to accumulate the data they will need to prove the safety of their unfiltered supplies. These examples and the accompanying bibliography that addresses the problems of meeting the new standards for unfiltered surface supplies can help utilities prepare for final implementation of the surface water treatment rule. Includes 10 references, tables, figures.