Environmental Protection Agency mandated by PL 92-500 to establish a National Pollutant Discharge Elimination System (NPDES) which involves specification of approved test procedures. This was ammended to include provisions allowing the use of alternate procedures. Both nationwide and limited use (specific permit holder) variances are involved. The recommended protocol for nationwide variance evaluation included sampling of five industrial effluent categories and possibly one municipal effluent. Six samples would be collected and analyzed in duplicate by both the proposed and approved analytical methods. Data evaluation would include a Moments test for normality followed by transformation, if required. The method comparison would involve a pared t-test and regression on the sample means. Data should be analyzed by industrial category and all together in order to identify if the method comparability was limited to certain discharges. Applicants for limited use variances would be required to sample fewer outfalls, however, six samples should be collected which reflect as wide a concentration range as possible. Data analysis is the same as that recommended for a nationwide variance. The recommended statistics were considered applicable for evaluating drinking water variance requests also, and some implementation procedures are included for this system.