HYDRO28691 - Laserfiche WebLink

Home Browse Search

COLORADO DEPARTMENT OF HEAL • er Quality Control Division • Rationale -Page 2, Permit No. CO-0029947 IIL- RECEIVING STREAM A. Identi/cation, Class~/icatton and Standards 1. Identification: Discharges are to Logan Wash, which is a tributary of Roan Creek Both Logan Wash and Roan Creek are in Segment 73 of the Zower Colorado River Basin loll tributaries to the Colorado River from a point irrvnediately bclaw the confluence ojParadune (}eek to the Calorado/Utah border), Region ll. 2. Clarsificarion: Segment 13 rs classified for the following uses: Use Protected; Recreation, Gass 2; Aquatic Lfe, Gass 2 (R'arm); Agriculture. 3. Numeric Standards: The complete list of standards which have been assigned lrt accordance with the about classfiaatian tan be found in 3.7.0, Class fications and Numeric Standards far the Lower Colorado River Basin (S CGt 1002-8), as amended September 7, 1993. The following numeric standards which have been assigned in accordance with the above classfkations will be used to develop effluent limitations. Physical and Biological D.O. = S.0 mg/l pH = 6. S - 9.0 s. u. Fecal Colijormr = 2000/100 ml There are no inorganic or metals standards for Segment 13 of the Lower Colorado River Basin which ineluder both Logan Wash and Roan Creek 77u near downstream segment with numeric standards is Segment 2 of the Lower Colorado River Basin. Due ro the absence of inorganic and metals standards for Segment 13, the previous permit adopted the numeric standards from Segmem 2 of Lower Colorado River to assist in ddnmining e,Qluent limitations and their effect on inter quality. The use of the Segmuu 2 numeric standards did not result in the incorporation of inter guality- based efjlutu limitations in the previous perntit due to their negligible impact on water quality. Using Best Professional ludganem, this permit renewal will not adopt the numeric standards for Segmem 2 of the Lower Colorado River in daerniining ejJGtent limitations. Factors influencing this decision include: (I) the ephemera! nature of the receiving stream; (1) the infrequent occurrence of discharges from Outfalis 001 and 002; (3) the 12 to I3 mile dutancc betwren the designated outfaAs and the confluence of Scgment 2 waters; (4J the high dilution provided by the Colorado River: However, Segment 2 standards arc referenced ar times within this rationale when discussing inter quality standards. In the event cirrmnstaxces change relating to potential impacts on the Colorado River in which Logan Wash mine site discharges either causes or contributes to these impacts, the Division reserves the right ra recalculate effluent limitations using the numeric standards established for Segment 2 ofthe Lower Colorado River. B. Receiving Water Data uali -Water quality data for Roan Creek near the town ofDebeque are available from USGS sampling station No. 09095000 and from WQ® station No. 000148 for the period from 1975 through 1985. This data was used in the previous permit ro assist in calculating water quality based limits. Water quality data is no longer collected at either station nor has receraly been collected eisewfiere within the Roan Creek drainage basin. The nearest USGS gauging station which collecu unto quality data is located downstream at the Colorado River below Clenxrood Springs, Colorado (USGS station No. 09085100). Flow at this location is not representative of flow at the discharge site. Therefore, only the 1975 through /985 water quality data for Segmem 13 is available for review purposes and will not be reprtmed in this rationale.