In Subsection R317-2-7(7.1), an explicit condition was added that when background concentration of a pollutant is higher than the applicable water quality criterion, the criterion will be the background concentration. This change is per USEPA Guidance and is intended to allow Utah to delist or not list waters where the exceedance of criteria is determined to be caused by natural conditions. Subsection R317-2-7(7.1) was reformatted into three subsections. This revision affects all waters of the state. In Section R317-2-14, Table 2.14.1, Footnote 4, the site-specific total dissolved solids criteria for Blue Creek, Box Elder County, were revised. The existing site-specific criteria are too low and based on historical total dissolved solids data would likely result in erroneously concluding that Blue Creek was impaired because ambient total dissolved solids concentrations exceed the state-wide 1,200 mg/l criterion. The proposed criteria are recalculated into two seasonal criteria, each having both maximum and average criteria. Comparison values for assessing against the average criteria are also included. The location of Blue Creek is corrected from Gunnison to Bear River Bay. In Section R317-2-14, Table 2.14.2, the aquatic life criteria for gross alpha were changed from criteria to indicators. The existing gross alpha criteria include a reference to Footnote 10, the same as all other indicators including gross beta demonstrating the intent that gross alpha should be interpreted as an indicator. USEPA has not promulgated aquatic life use criteria for gross alpha or beta. The result is that gross alpha will be an indicator for Class 3 aquatic life uses but remains as criteria for Class 1C and Class 4 waters. This revision affects all waters of the state. In Section R317-2-14, Table 2.14.2, Footnote 13 was deleted because the formula for calculating hydrogen sulfide could not be verified in either USEPA or Standard Methods and produces erroneous results at low pH. Absent the footnote, hydrogen sulfide concentrations will be determined in accordance with approved analytical methods. This revision affects all Waters of the State. In Section R317-2-14, Table 2.14.3b, missing parentheses were added to correct formulas for calculating acute aquatic life criteria for nickel, silver, and zinc. These corrections affect all waters of the state.