A paper contributed to and selected by the JOURNAL, authored by Stephen R. Jenkins (Active Member, AWWA), asst. prof., Dept. of Civ, Engrg., Auburn Univ., Auburn, Ala., and Jogeir Engeset (Student Member, AWWA), res., asst., Univ. of Washington, Seattle, Wash.In a recent study the cost of treating naturally occurring waters of Wyoming was shown to be small if rapid sand filtration plants were available. Unfortu nately, most Wyoming communities do not have existing sand filtration plants and therefore, the removal of manga nese by this method is uneconomical. Generally the benefit gained by remov ing the manganese will usually not justify the expense of building a filter plant solely for that purpose.