HYDRO20139

• Permit No: C1980007
• IBM Index Class Name: Hydrology
• Doc Date: 12/12/2005
• Doc Name: Discharge Permit CO-0038776
• From: Colorado Department of Public Health
• To: Mountain Coal Company, LLC
• Permit Index Doc Type: NPDES
• Media Type: D
• Archive: No

Mountain Coal and Bear Coal Water Quality Assessment CO-0038776 and CO-0044377
Table A-4
TVS-Based Metals Water Quality Standards for the North Fork of the Gunnison River
Based on the Table Value Standards Contained in the Colorado Department of Public Health
and Environment Water ality Control Commission Regulation 35
Calculated Using the Following Value for Hardness as CaCO3: 52~mpQ
Cadmium, Dissolved
Hexavalent Chron3itnn,
Dissolved
Copper, Dissolved
Lead, Dissolved
Manganese
_ Nickel, Dissolved
Selenitrzn, Dissolved
Sliver, Dissolved
Zinc, Dissolved
Trout 1.8
Chronic 1.4
Acute 16
Chronic I1
Acute 7.3
Chromc 5.1
Acute 31
Chronic 1.2
Acute 2401
Acute 269
Acute
Cl]rO1nC
[1.13667-0.041841n(ha
'].10167-D.041841n(har
Numeric standards
Numeric standards
e (0.942
(I ,128 (ln (hardness))-3.828 )]
;0.7 852 (In(hardness))-2.715),
form ufa not applicable
formula not applicable
e (0.8545(ln(hardness))-1.7428)
[1.46203-0.1457121n (hardness)][e` ~ ~ `
1.46203-0.1457121n(hardness)][e (1.273(In(har
e (0.3331(ln (hardness))+6.4676)
e
~ul ugil e'---~--~--------~-----
l gl Ug/1 Numeric standards provided, formula not
4.6 ug/1 Numeric standards provided, formula not
0.66 ug/1 Is a (1.72(In(hardness))-6.52)
0.024~ ug/1 e(1.72(ln(hardness))-10.51)
67~ llg/1 e(0.8473(]n(hardness))+0.8618
6$~ 13g.A _ e(0.8473(In(hardness))+0.8699
46)]
In the absence of available data downstream of discharge locations, the mean hardness for stream
segment COGLTNF06 (including Sylvester Gulch, West Sylvester Gulch, the DryFork of Minnesota
Creek, and Lone Pine Gulch) was determined to be 400 mg/1 based on the Rationale for
Class cations, Standards and Designations of Segments of the Gunnison and LowerpoloresRiver
Basins, which determined this hazdness for stream segment COGUNF06 using comparable
watersheds, This hazdness value and the formulas contained in the'I'VS were used to calculate the
in-stream water quality standazds for metals with the results shown in Table A-5.
Appendix A Page 7 of 20 Last Revised 3/9/2004