The applicability of the U.S Environmental Rotection Agency's (USEPA) water temperature criteria in evaluating the impact of a thermal discharge from the P. H. Glatfelter Paper Company, Spring Grove, Pennsylvania, is analyzed. A review of the literature relative to 11 temperature Criteria was conducted for six fish species designated by the USEPA as "representative important species" (RIS) of the West Branch Codorus Creek, Susquehanna River drainage. The species were: Notemigonus crysolcucas (golden shiner), Nofropis armlosfanus (satinfin shiner), Rhinichthys atrafulus (blacknose dace), Cbtostoms commersoni (white sucker), LepomiJ gibborus @umpkinseed). and Microp fernus wlmoides (largemouth bass). It was found that by applying only USEPA suggested criteria that a complete evaluation was not satisfactory. Temperature behavior data, specifically preference and avoidance information, coupled with field sampliug was needed to properly assess the effects of the thermal effluent. The final analysis indicated that the thermal discharge of the paper company should have miuimal effect on the fish community of Codorus Creek. (KEY TERMS: temperature Criteria; thermal behavior; thermal discharges; biological integrity.) 'Paper No. 81054 of the Wufer R e s o w s Bulletin. Discussions are open until February 1,1983. 'Respectively, West Branch Codom at Menges Mills, Pennsylvania, immediately below confluence with Oil Creek Oil Creek, approximately 0.5 km above confluence with West BranchCodorusCreek ~ West Branch Codorus at head of Mill Pond, Spring Grove, Pennsylvania West Branch CO~OIUS at Mill Pond (PHGC Filter Plant), Spring Grove, Pennsylvania West Branch Codorus at Mill Pond (PHGC Power House), Spring Grove, Pennsylvania