COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT 
WATER QUALITY CONTROL COMMISSION 
5 CCR 1002-36
REGULATION NO. 36
CLASSIFICATIONS AND NUMERIC STANDARDS
FOR
RIO GRANDE RIVER BASIN
. . . .
36.6 	TABLES
. . . .
(2)	Abbreviations:
. . . .
(d)	Temporary Modification for Water + Fish Chronic Arsenic Standard
(i)	The temporary modification for chronic arsenic standards applied to segments with an arsenic standard of 0.02 mg/l that has been set to protect the Water+Fish qualifier is listed in the temporary modification and qualifiers column as As(ch)=hybrid.
(ii)	For discharges existing on or before 6/1/2013, the temporary modification is:  As(ch)=current condition, expiring on 12/31/2021.
(iii)	For new or increased discharges commencing on or after 6/1/2013, the temporary modification is:  As(ch)=0.02-3.0 mg/l (Trec), expiring on 12/31/2021.
(a)	The first number in the range is the health-based water quality standard previously adopted by the Commission for the segment.
(b)	The second number in the range is a technology based value established by the Commission for the purpose of this temporary modification.
(c)	Control requirements, such as discharge permit effluent limitations, shall be established using the first number in the range as the ambient water quality target, provided that no effluent limitation shall require an “end-of-pipe” discharge level more restrictive than the second number in the range.
(3)	Table Value Standards
. . . .

REGION: 8

BASIN: Rio Grande	Desig	Classifications	NUMERIC STANDARDS	TEMPORARY
MODIFICATIONS
AND
QUALIFIERS	
			PHYSICAL
and
BIOLOGICAL	INORGANIC
mg/l	METALS
ug/l		
Stream Segment Description							

1.	All tributaries to the Rio Grande, including all wetlands, lakes and reservoirs, which are within the Weminuche Wilderness Area. 	

OW	
Aq Life Cold 1
Recreation E
Water Supply
Agriculture	
D.O. = 6.0 mg/l
D.O. (sp)=7.0 mg/l
pH = 6.5-9.0
E.Coli=126/100ml	
NH3(ac/ch)=TVS
Cl2(ac)=0.019
Cl2(ch)=0.011
CN=0.005	
S=0.002
B=0.75
NO2=0.05
NO3=10
Cl=250
SO4=WS	
As(ac)=340
As(ch)=0.02(Trec)
Cd(ac)=TVS(tr)
Cd(ch)=TVS
CrIII(ac)=50(Trec)
CrVI(ac/ch)=TVS
	
Cu(ac/ch)=TVS
Fe(ch)=WS(dis)
Fe(ch)=1000(Trec)
Pb(ac/ch)=TVS
Mn(ch)=WS(dis)
Mn(ac/ch)=TVS	
Hg(ch)=0.01(Trec)
Ni(ac/ch)=TVS
Se(ac/ch)=TVS
Ag(ac)=TVS
Ag(ch)=TVS(tr)
Zn(ac/ch)=TVS	

Temporary modification:
As(ch)=hybrid
Expiration date of 12/31/21.	

2.	Mainstem of the Rio Grande, including all wetlands, tributaries, lakes and reservoirs, from the source to a point immediately above the confluence with Willow Creek except for the specific listings in segments 1 and 3.	
	
Aq Life Cold 1
Recreation E
Water Supply
Agriculture	
D.O. = 6.0 mg/l
D.O. (sp)=7.0 mg/l
pH = 6.5-9.0
E.Coli=126/100ml	
NH3(ac/ch)=TVS
Cl2(ac)=0.019
Cl2(ch)=0.011
CN=0.005	
S=0.002
B=0.75
NO2=0.05
NO3=10
Cl=250
SO4=WS	
As(ac)=340
As(ch)=0.02(Trec)
Cd(ac)=TVS(tr)
Cd(ch)=TVS
CrIII(ac)=50(Trec)
CrVI(ac)/ch)=TVS
Cu(ac/ch)=TVS	
Fe(ch)=WS(dis) 
Fe(ch)=1000(Trec)
Pb(ac/ch)=TVS
Mn(ch)=WS(dis)
Mn(ac/ch)=TVS	
Hg(ch)=0.01(Trec)
Ni(ac/ch)=TVS
Se(ac/ch)=TVS
Ag(ac)=TVS
Ag(ch)=TVS(tr)
Zn(ac/ch)=TVS	

Temporary modification:
As(ch)=hybrid
Expiration date of 12/31/21.	

4.	Mainstem of the Rio Grande from a point immediately above the confluence with Willow Creek to the Rio Grande/Alamosa County line.	
	
Aq Life Cold 1
Recreation E
Water Supply
Agriculture	
D.O. = 6.0 mg/l
D.O. (sp)=7.0 mg/l
pH = 6.5-9.0
E.Coli=126/100ml	
NH3(ac/ch)=TVS
Cl2(ac)=0.019
Cl2(ch)=0.011
CN=0.005	
S=0.002
B=0.75
NO2=0.05
NO3=10
Cl=250
SO4=WS	
As(ac)=340
As(ch)=0.02(Trec)
Cd(ac)=TVS(tr)
Cd(ch)=TVS
CrIII(ac)=50(Trec)
CrVI(ac/ch)=TVS
Cu(ac/ch)=TVS	
Fe(ch)=WS(dis) 
Fe(ch)=1000(Trec)
Pb(ac/ch)=TVS
Mn(ch)=WS(dis)
Mn(ac/ch)=TVS	
Hg(ch)=0.01(Trec)
Ni(ac/ch)=TVS
Se(ac/ch)=TVS
Ag(ac)=TVS
Ag(ch)=TVS(tr)
Zn(ac/ch)=TVS	
Temporary Modifications type iii:
Cd(ch)=existing quality
Cu(ch)=existing quality
Pb(ch)=existing quality
Zn(ch)=existing quality
Expiration Date of 12/31/2013

Temporary modification:
As(ch)=hybrid
Expiration date of 12/31/21.

5.	All tributaries to the Rio Grande, including all wetlands, lakes and reservoirs, from immediately above the confluence with Willow Creek to State Highway 112 bridge in Del Norte, except for specific listings in segments 6 through 10.	
	
Aq Life Cold 1
Recreation E
Water Supply
Agriculture	
D.O. = 6.0 mg/l
D.O. (sp)=7.0 mg/l
pH = 6.5-9.0
E.Coli=126/100ml	
NH3(ac/ch)=TVS
Cl2(ac)=0.019
Cl2(ch)=0.011
CN=0.005	
S=0.002
B=0.75
NO2=0.05
NO3=10
Cl=250 
SO4=WS	
As(ac)=340
As(ch)=0.02(Trec)
Cd(ac)=TVS(tr)
Cd(ch)=TVS
CrIII(ac)=50(Trec)
CrVI(ac/ch)=TVS
Cu(ac/ch)=TVS	
Fe(ch)=WS(dis) 
Fe(ch)=1000(Trec)
Pb(ac/ch)=TVS
Mn(ch)=WS(dis)
Mn(ac/ch)=TVS	
Hg(ch)=0.01(Trec)
Ni(ac/ch)=TVS
Se(ac/ch)=TVS
Ag(ac)=TVS
Ag(ch)=TVS(tr)
Zn(ac/ch)=TVS	

Temporary modification:
As(ch)=hybrid
Expiration date of 12/31/21.	

9.	Mainstem of the South Fork of Rio Grande, including all tributaries, wetlands, lakes and reservoirs, from source to confluence with Rio Grande except segment 1.	
	
Aq Life Cold 1
Recreation E
Water Supply
Agriculture	
D.O. = 6.0 mg/l
D.O. (sp)=7.0 mg/l
pH = 6.5-9.0
E.Coli=126/100ml	
NH3(ac/ch)=TVS
Cl2(ac)=0.019
Cl2(ch)=0.011
CN=0.005	
S=0.002
B=0.75
NO2=0.05
NO3=10
Cl=250
SO4=WS	
As(ac)=340
As(ch)=0.02(Trec)
Cd(ac)=TVS(tr)
Cd(ch)=TVS
CrIII(ac)=50(Trec)
CrVI(ac/ch)=TVS     Cu(ac/ch)=TVS	
Fe(ch)=WS(dis)
Fe(ch)=1000(Trec)
Pb(ac/ch)=TVS
Mn(ch)=WS(dis)
Mn(ac/ch)=TVS	
Hg(ch)=0.01(Trec)
Ni(ac/ch)=TVS
Se(ac/ch)=TVS
Ag(ac)=TVS
Ag(ch)=TVS(tr)
Zn(ac/ch)=TVS	

Temporary modification:
As(ch)=hybrid
Expiration date of 12/31/21.	

11.	Mainstem of San Francisco Creek (Rio Grande County), including all tributaries, wetlands, lakes and reservoirs, from the source to the confluence with Spring Branch.	
	
Aq Life Cold 1
Recreation E
Water Supply
Agriculture	
D.O. = 6.0 mg/l
D.O.(sp)=7.0 mg/l
pH = 6.5-9.0
E.Coli=126/100ml	
NH3(ac/ch)=TVS
Cl2(ac)=0.019
Cl2(ch)=0.011
CN=0.005	
S=0.002
B=0.75
NO2=0.05
NO3=10
Cl=250
SO4=WS	
As(ac)=340
As(ch)=0.02(Trec)
Cd(ac)=TVS(tr)
Cd(ch)=TVS
CrIII(ac)=50(Trec)
CrVI(ac)/ch)=TVS
Cu(ac/ch)=TVS	
Fe(ch)=WS(dis)
Fe(ch)=1000(Trec)
Pb(ac/ch)=TVS
Mn(ch)=WS(dis)
Mn(ac/ch)=TVS	
Hg(ch)=0.01(Trec)
Ni(ac/ch)=TVS
Se(ac/ch)=TVS
Ag(ac)=TVS
Ag(ch)=TVS(tr)
Zn(ac/ch)=TVS	

Temporary modification:
As(ch)=hybrid
Expiration date of 12/31/21.	

14.	All tributaries to the Rio Grande including wetlands, lakes and reservoirs, which are within the Rio Grande National Forest, from the State Highway 112 bridge in Del Norte to immediately below the confluence of Rock Creek with the Rio Grande, except for specific listings in segments 11, 19 and 20.	
	
Aq Life Cold 1
Recreation E
Water Supply
Agriculture	
D.O.=6.0 mg/l
D.O.(sp)=7.0 mg/l
pH = 6.5-9.0
E.Coli=126/100ml	
NH3(ac/ch)=TVS
Cl2(ac)=0.019
Cl2(ch)=0.011
CN=0.005	
S=0.002
B=0.75
NO2=0.05
NO3=10
Cl=250
SO4=WS	
As(ac)=340
As(ch)=0.02(Trec)
Cd(ac)=TVS(tr)
Cd(ch)=TVS
CrIII(ac)=50(Trec)
CrVI(ac/ch)=TVS
Cu(ac/ch)=TVS	
Fe(ch)=WS(dis)
Fe(ch)=1000(Trec)
Pb(ac/ch)=TVS
Mn(ch)=WS(dis)
Mn(ac/ch)=TVS	
Hg(ch)=0.01(Trec)
Ni(ac/ch)=TVS
Se(ac/ch)=TVS
Ag(ac)=TVS
Ag(ch)=TVS(tr)
Zn(ac/ch)=TVS	

Temporary modification:
As(ch)=hybrid
Expiration date of 12/31/21.	

19.	Mainstem of Rock Creek, including all tributaries, wetlands, lakes and reservoirs from source to Monte Vista Canal.	
	
Aq Life Cold 1
Recreation E
Water Supply
Agriculture	
D.O. = 6.0 mg/l
D.O. (sp)=7.0 mg/l
pH = 6.5-9.0
E.Coli=126/100ml	
NH3(ac/ch)=TVS
Cl2(ac)=0.019
Cl2(ch)=0.011
CN=0.005	
S=0.002
B=0.75
NO2=0.05
NO3=10
Cl=250
SO4=WS	
As(ac)=340
As(ch)=0.02(Trec)
Cd(ac)=TVS(tr)
Cd(ch)=TVS
CrIII(ac)=50(Trec)
CrVI(ac/ch)=TVS
Cu(ac/ch)=TVS	
Fe(ch)=WS(dis)
Fe(ch)=1000(Trec)
Pb(ac/ch)=TVS
Mn(ch)=WS(dis)
Mn(ac/ch)=TVS	
Hg(ch)=0.01(Trec)
Ni(ac/ch)=TVS
Se(ac/ch)=TVS
Ag(ac)=TVS
Ag(ch)=TVS(tr)
Zn(ac/ch)=TVS	

Temporary modification:
As(ch)=hybrid
Expiration date of 12/31/21.	

21.	Mainstem of Ute Creek, including all tributaries, wetlands, lakes and reservoirs, from the source to U.S. Hwy 160.	
	
Aq Life Cold 1
Recreation E
Water Supply
Agriculture	
D.O. = 6.0 mg/l
D.O. (sp)=7.0 mg/l
pH = 6.5-9.0
E.Coli=126/100ml	
NH3(ac/ch)=TVS
Cl2(ac)=0.019
Cl2(ch)=0.011
CN=0.005	
S=0.002
B=0.75
NO2=0.05
NO3=10
Cl=250
SO4=WS	
As(ac)=340
As(ch)=0.02(Trec)
Cd(ac)=TVS(tr)
Cd(ch)=TVS
CrIII(ac)=50(Trec)
CrVI(ac/ch)=TVS
Cu(ac/ch)=TVS	
Fe(ch)=WS(dis)
Fe(ch)=1000(Trec)
Pb(ac/ch)=TVS
Mn(ch)=WS(dis)
Mn(ac/ch)=TVS	
Hg(ch)=0.01(Trec)
Ni(ac/ch)=TVS
Se(ac/ch)=TVS
Ag(ac)=TVS
Ag(ch)=TVS(tr)
Zn(ac/ch)=TVS	

Temporary modification:
As(ch)=hybrid
Expiration date of 12/31/21.	

28.	Mainstem of Rito Seco, including all tributaries, wetlands, lakes and reservoirs, from the source to the outlet of Salzar Reservoir.	
	
Aq Life Cold 1
Recreation E
Water Supply
Agriculture	
D.O. = 6.0 mg/l
D.O.(sp)=7.0 mg/l
pH = 6.5-9.0
E.Coli=126/100ml	
NH3(ac/ch)=TVS
Cl2(ac)=0.019
Cl2(ch)=0.011
CN=0.005	
S=0.002
B=0.75
NO2=0.05
NO3=10
Cl=250
SO4=WS	
As(ac)=340
As(ch)=0.02(Trec)
Cd(ac)=TVS(tr)
Cd(ch)=TVS
CrIII(ac)=50(Trec)
CrVI(ac)/ch)=TVS
Cu(ac/ch)=TVS	
Fe(ch)=WS(dis)
Fe(ch)=1000(Trec)
Pb(ac/ch)=TVS
Mn(ch)=WS(dis)
Mn(ac/ch)=TVS	
Hg(ch)=0.01(Trec)
Ni(ac/ch)=TVS
Se(ac/ch)=TVS
Ag(ac)=TVS
Ag(ch)=TVS(tr)
Zn(ac/ch)=TVS	

Temporary modification:
As(ch)=hybrid
Expiration date of 12/31/21.	

30.	Mainstem of Culebra Creek, including all tributaries, wetlands, lakes and reservoirs, from the source to State Highway 159 except segments 28 and 29, mainstem and all tributaries of Costilla Creek in Colorado to 7 Road.	
	
Aq Life Cold 1
Recreation E
Water Supply
Agriculture
	
D.O. = 6.0 mg/l
D.O.(sp)=7.0 mg/l
pH = 6.5-9.0
E.Coli=126/100ml	
NH3(ac/ch)=TVS
Cl2(ac)=0.019
Cl2(ch)=0.011
CN=0.005	
S=0.002
B=0.75
NO2=0.05
NO3=10
Cl=250
SO4=WS	
As(ac)=340
As(ch)=0.02(Trec)
Cd(ac)=TVS(tr)
Cd(ch)=TVS
CrIII(ac)=50(Trec)
CrVI(ac)/ch)=TVS
Cu(ac/ch)=TVS	
Fe(ch)=WS(dis)
Fe(ch)=1000(Trec)
Pb(ac/ch)=TVS
Mn(ch)=WS(dis)
Mn(ac/ch)=TVS
	
Hg(ch)=0.01(Trec)
Ni(ac/ch)=TVS
Se(ac/ch)=TVS
Ag(ac)=TVS
Ag(ch)=TVS(tr)
Zn(ac/ch)=TVS	

Temporary modification:
As(ch)=hybrid
Expiration date of 12/31/21.	

REGION: 8

BASIN: Alamosa River/La Jara Creek/Conejos River	Desig	Classifications	NUMERIC STANDARDS	TEMPORARY
MODIFICATIONS
AND
QUALIFIERS	
			PHYSICAL
and
BIOLOGICAL	INORGANIC
mg/l	METALS
ug/l		
Stream Segment Description							

13.	Mainstem Hot Creek from source to confluence with La Jara Creek.	
	
Aq Life Cold 1
Recreation E
Water Supply
Agriculture	
D.O. = 6.0 mg/l
D.O.(sp)=7.0 mg/l
pH=6.5-9.0
E.Coli=126/100ml	
NH3(ac/ch)=TVS
Cl2(ac)=0.019
Cl2(ch)=0.011
CN=0.005	
S=0.002
B=0.75
NO2=0.05
NO3=10
Cl=250
SO4=WS	
As(ac)=340
As(ch)=0.02(Trec)
Cd(ac)=TVS(tr)
Cd(ch)=TVS
CrIII(ac)=50(Trec)
CrVI(ac/ch)=TVS
Cu(ac/ch)=TVS	
Fe(ch)=WS(dis)
Fe(ch)=1000(Trec)
Pb(ac/ch)=TVS
Mn(ch)=WS(dis)
Mn(ac/ch)=TVS
Hg(ch)=0.01(Trec)	
Ni(ac/ch)=TVS
Se(ac/ch)=TVS
Ag(ac)=TVS
Ag(ch)=TVS(tr)
Zn(ac/ch)=TVS	

Temporary modification:
As(ch)=hybrid
Expiration date of 12/31/21.	

14.	Mainstem of Conejos River including all tributaries, wetlands, lakes and reservoirs, from source to immediately above the confluence with Fox Creek except for specific listing in segment 1.	
	
Aq Life Cold 1
Recreation E
Water Supply
Agriculture	
D.O. = 6.0 mg/l
D.O.(sp)=7.0 mg/l
pH = 6.5-9.0
E.Coli=126/100ml	
NH3(ac/ch)=TVS
Cl2(ac)=0.019
Cl2(ch)=0.011
CN=0.005	
S=0.002
B=0.75
NO2=0.05
NO3=10
Cl=250
SO4=WS	
As(ac)=340
As(ch)=0.02(Trec)
Cd(ac)=TVS(tr)
Cd(ch)=TVS
CrIII(ac)=50(Trec)
CrVI(ac)/ch)=TVS
Cu(ac/ch)=TVS	
Fe(ch)=WS(dis)
Fe(ch)=1000(Trec)
Pb(ac/ch)=TVS
Mn(ch)=WS(dis)
Mn(ac/ch)=TVS
Hg(ch)=0.01(Trec)	
Ni(ac/ch)=TVS
Se(ac/ch)=TVS
Ag(ac)=TVS
Ag(ch)=TVS(tr)
Zn(ac/ch)=TVS	

Temporary modification:
As(ch)=hybrid
Expiration date of 12/31/21.	

15.	Mainstem of Conejos River from a point immediately above the confluence with Fox Creek to the confluence with the San Antonio River.		
Aq Life Cold 2
Recreation E
Water Supply
Agriculture	
D.O. = 6.0 mg/l
D.O. (sp)=7.0 mg/l
pH = 6.5-9.0
E.Coli=126/100ml	
NH3(ac/ch)=TVS
Cl2(ac)=0.019
Cl2(ch)=0.011
CN=0.005	
S=0.002
B=0.75
NO2=0.05
NO3=10
Cl=250
SO4=WS	
As(ac)=340
As(ch)=0.02(Trec)
Cd(ac)=TVS(tr)
Cd(ch)=TVS
CrIII(ac)=50(Trec)
CrVI(ac/ch)=TVS
Cu(ac/ch)=TVS	
Fe(ch)=WS(dis)
Fe(ch)=1000(Trec)
Pb(ac/ch)=TVS
Mn(ch)=WS(dis)
Mn(ac/ch)=TVS
Hg(ch)=.01(Trec)	
Ni(ac/ch)=TVS
Se(ac/ch)=TVS
Ag(ac)=TVS
Ag(ch)=TVS(tr)
Zn(ac/ch)=TVS	
Fish Ingestion

Temporary modification:
As(ch)=hybrid
Expiration date of 12/31/21.	

17.	Mainstem of Rio de Los Pinos, including all tributaries, wetlands, lakes and reservoirs, from the source to the New Mexico border, except for specific listings in segment 1.  Mainstem of the Rio San Antonio from the New Mexico border to Highway 285.	
	
Aq Life Cold 1
Recreation E
Water Supply
Agriculture	
D.O. = 6.0 mg/l
D.O.(sp)=7.0 mg/l
pH = 6.5-9.0
E.Coli=126/100ml	
NH3(ac/ch)=TVS
Cl2(ac)=0.019
Cl2(ch)=0.011
CN=0.005	
S=0.002
B=0.75
NO2=0.05
NO3=10
Cl=250
SO4=WS	
As(ac)=340
As(ch)=0.02(Trec)
Cd(ac)=TVS(tr)
Cd(ch)=TVS
CrIII(ac)=50(Trec)
CrVI(ac)/ch)=TVS
Cu(ac/ch)=TVS	
Fe(ch)=WS(dis)
Fe(ch)=1000(Trec)
Pb(ac/ch)=TVS
Mn(ch)=WS(dis)
Mn(ac/ch)=TVS
Hg(ch)=0.01(Trec)
	
Ni(ac/ch)=TVS
Se(ac/ch)=TVS
Ag(ac)=TVS
Ag(ch)=TVS(tr)
Zn(ac/ch)=TVS	

Temporary modification:
As(ch)=hybrid
Expiration date of 12/31/21.	

20.	All tributaries to the Rio Grande, including wetlands, lakes and reservoirs, which are within the Rio Grande National Forest, except for specific listings in segments 1 through 7, 11, 13, 14, 17, and 19.	
	
Aq Life Cold 1
Recreation E
Water Supply
Agriculture	
D.O. = 6.0 mg/l
D.O.(sp)=7.0 mg/l
pH = 6.5-9.0
E.Coli=126/100ml	
NH3(ac/ch)=TVS
Cl2(ac)=0.019
Cl2(ch)=0.011
CN=0.005	
S=0.002
B=0.75
NO2=0.05
NO3=10
Cl=250
SO4=WS	
As(ac)=340
As(ch)=0.02(Trec)
Cd(ac)=TVS(tr)
Cd(ch)=TVS
CrIII(ac)=50(Trec)
CrVI(ac/ch)=TVS
Cu(ac/ch)=TVS	
Fe(ch)=WS(dis)
Fe(ch)=1000(Trec)
Pb(ac/ch)=TVS
Mn(ch)=WS(dis)
Mn(ac/ch)=TVS
Hg(ch)=0.01(Trec)	
Ni(ac/ch)=TVS
Se(ac/ch)=TVS
Ag(ac)=TVS
Ag(ch)=TVS(tr)
Zn(ac/ch)=TVS	

Temporary modification:
As(ch)=hybrid
Expiration date of 12/31/21.	

REGION: 8

BASIN: Closed Basin-San Luis Valley	Desig	Classifications	NUMERIC STANDARDS	TEMPORARY
MODIFICATIONS
AND
QUALIFIERS	
			PHYSICAL
and
BIOLOGICAL	INORGANIC
mg/l	METALS
ug/l		
Stream Segment Description							

4.	Mainstem of San Luis Creek, including all tributaries, wetlands, lakes and reservoirs, from the source to a point immediately below the confluence with Piney Creek except for segments 8, 9a and 9b.	
	
Aq Life Cold 1
Recreation E
Water Supply
Agriculture	
D.O. = 6.0 mg/l
D.O. (sp)=7.0 mg/l
pH = 6.5-9.0
E.Coli=126/100ml	
NH3(ac/ch)=TVS
Cl2(ac)=0.019
Cl2(ch)=0.011
CN=0.005	
S=0.002
B=0.75
NO2=0.05
NO3=10
Cl=250
SO4=WS	
As(ac)=340
As(ch)=0.02(Trec)
Cd(ac)=TVS(tr)
Cd(ch)=TVS
CrIII(ac)=50(Trec)
CrVI(ac/ch)=TVS
Cu(ac/ch)=TVS	
Fe(ch)=WS(dis)
Fe(ch)=1000(Trec)
Pb(ac/ch)=TVS
Mn(ch)=WS(dis)
Mn(ac/ch)=TVS
Hg(ch)=0.01(Trec)	
Ni(ac/ch)=TVS
Se(ac/ch)=TVS
Ag(ac)=TVS
Ag(ch)=TVS(tr)
Zn(ac/ch)=TVS	

Temporary modification:
As(ch)=hybrid
Expiration date of 12/31/21.	

9b.	Mainstem of Kerber Creek from the confluence with Brewery Creek  to the confluence with San Luis Creek.	

UP	
Aq Life Cold 1
Recreation E
Water Supply*
Agriculture*	
D.O. = 6.0 mg/l
D.O.(sp)=7.0 mg/l
pH = 6.5-9.0
E.Coli=126/100ml	
NH3(ac/ch)=TVS
Cl2(ac)=0.019
Cl2(ch)=0.011
CN=0.005	
S=0.002
B=0.75
NO2=0.05
NO3=10
Cl=250
SO4=WS	
As(ac)=340 As(ch)=0.02(Trec)
CrIII(ac)=50(Trec)
CrVI(ac/ch)=TVS
Cu(ac/ch)=TVS	
Fe(ch)=1000(Trec)
Fe(ch)=300(dis)
Pb(ac/ch)=TVS
Mn(ch)=WS(dis)
Mn(ac/ch)=TVS
Hg(ch)=0.01(Trec)	
Ni(ac/ch)=TVS
Se(ac/ch)=TVS
Ag(ac)=TVS
Ag(ch)=TVS(tr)
Zn(ac/ch)=TVS
	
*Goal Qualifier: All metals are Trec unless otherwise noted.

	

	

Cd(ac)=e(0.7852ln[hard]-1.545)
Cd(ch)=e(0.7852ln[hard]-2.906)
Cu(ac)=e(0.8889ln[hard]+0.53)
Cu(ch)=e(0.8889ln[hard]-1.519)
Zn(ac)=e(0.8179ln[hard]+3.757)
  Zn(ch)=e(0.8179ln[hard]+2.907)		Temporary modification:
As(ch)=hybrid
Expiration date of
12/31/21.	

11.	All tributaries to the Closed Basin within the Rio Grande National Forest boundaries except segments 1, 2, 4, 9, 10, and 12.	
	
Aq Life Cold 1
Recreation E
Water Supply
Agriculture	
D.O. = 6.0 mg/l
D.O.(sp)=7.0 mg/l
pH = 6.5-9.0
E.Coli=126/100ml	
NH3(ac/ch)=TVS
Cl2(ac)=0.019
Cl2(ch)=0.011
CN=0.005	
S=0.002
B=0.75
NO2=0.05
NO3=10
Cl=250
SO4=WS	
As(ac)=340
As(ch)=0.02(Trec)
Cd(ac)=TVS(tr)
Cd(ch)=TVS
CrIII(ac)=50(Trec)
CrVI(ac)/ch)=TVS
Cu(ac/ch)=TVS	
Fe(ch)=WS(dis)
Fe(ch)=1000(Trec)
Pb(ac/ch)=TVS
Mn(ch)=WS(dis)
Mn(ac/ch)=TVS
Hg(ch)=0.01(Trec)	
Ni(ac/ch)=TVS
Se(ac/ch)=TVS
Ag(ac)=TVS
Ag(ch)=TVS(tr)
Zn(ac/ch)=TVS	

Temporary modification:
As(ch)=hybrid
Expiration date of 12/31/21.	

12.	Mainstem of Saguache Creek from the boundary of the La Garita Wilderness Area to Hwy 285; all tributaries to Saguache Creek, including all wetlands, lakes and reservoirs, from the source to a point immediately below the confluence with Ford Creek, expect for the specific listing in segment 1.	
	
Aq Life Cold 1
Recreation E
Water Supply
Agriculture	
D.O. = 6.0 mg/l
D.O. (sp)=7.0 mg/l
pH = 6.5-9.0
E.Coli=126/100ml	
NH3(ac/ch)=TVS
Cl2(ac)=0.019
Cl2(ch)=0.011
CN=0.005	
S=0.002
B=0.75
NO2=0.05
NO3=10
Cl=250
SO4=WS	
As(ac)=340
As(ch)=0.02(Trec)
Cd(ac)=TVS(tr)
Cd(ch)=TVS
CrIII(ac)=50(Trec)
CrVI(ac/ch)=TVS
Cu(ac/ch)=TVS	
Fe(ch)=WS(dis)
Fe(ch)=1000(Trec)
Pb(ac/ch)=TVS
Mn(ch)=WS(dis)
Mn(ac/ch)=TVS
Hg(ch)=0.01(Trec)	
Ni(ac/ch)=TVS
Se(ac/ch)=TVS
Ag(ac)=TVS
Ag(ch)=TVS(tr)
Zn(ac/ch)=TVS	

Temporary modification:
As(ch)=hybrid
Expiration date of 12/31/21.	

. . . .
36.33	STATEMENT OF BASIS SPECIFIC STATUTORY AUTHORITY AND PURPOSE APRIL 8, 2013 RULEMAKING; FINAL ACTION MAY 13, 2013 EFFECTIVE DATE SEPTEMBER 30, 2013
The provisions of C.R S. 25-8-202(1)(a), (b) and (2); 25-8-203; 25-8-204; and 25-8-402; provide the specific statutory authority for adoption of these regulatory amendments.  The Commission also adopted in compliance with 24-4-103(4) C.R.S. the following statement of basis and purpose.
BASIS AND PURPOSE
In August of 2005, the Commission adopted revisions to the Basic Standards and Methodologies for Surface Waters (Regulation #31) to add a Water + Fish (W+F) table value standard for chronic arsenic of 0.02 micrograms per liter (μg/L). W+F standards are numeric human health-based water quality standards that are calculated protective values that take into account the combined exposure from the pollutant in drinking water and the pollutant accumulated in fish flesh. This criterion automatically went into effect for Aquatic Life Class 1 waters which also have a Domestic Water Supply use, when the changes to the Basic Standards became effective.  It was also adopted on a segment by segment basis for Aquatic Life class 2 waters with Domestic Water Supply where the Commission determined there are fish of a catchable size of species that are normally consumed.  Because of the complicated nature of the arsenic standards, specific values were added to the basin tables in the basin hearings between 2006 and 2009.
In this hearing, the Commission adopted temporary modifications for W+F chronic arsenic where a permitted discharger with a water quality–based effluent limit compliance problem exists. The adopted temporary modification is listed in the regulation tables as “As(ch)=hybrid”. An explanation of the temporary modification and its expected implementation into control requirements, such as Colorado Discharge Permit System (CDPS) effluent limitations, is described in 36.6(2)(d). The temporary modification was established by the Commission to allow for a temporarily less stringent application of the chronic arsenic standard in control requirements for both existing discharges and new or increased discharges. 
For discharges existing on or before 6/1/2013, the temporary modification adopted for W+F chronic arsenic is “current condition”, expiring on 12/31/2021. The Commission intends that, when implementing the temporary modification of “current condition” in a CDPS permit, the Division will assess the current effluent quality, recognizing that it changes over time due to variability in treatment facility removal efficiency and influent loading from natural or anthropogenic sources, and due to changes in the influent flow and concentration over time. Maintaining the current condition will include maintaining permitted total arsenic loading to a treatment facility from arsenic contributors at the levels existing on the effective date of the temporary modification, while expressly allowing for variability in such loading due to changes in effluent quality as described above and due to changes in the influent flow and concentration over time within the permitted design flow of that facility. The Commission understands that the Division's past practice implementing this requirement in permits has been through reporting regarding the arsenic loading to the facility, and not through numeric effluent limitations. The Commission intends that the Division will continue this practice. For facilities that lack enough representative data to quantify arsenic loading, the permittee may satisfy reporting requirements through narrative descriptions of potential sources of arsenic. No permit action shall be approved that allows an increase in permitted total arsenic loading to a treatment facility. The expiration date of the temporary modification was set at 12/31/21 to allow for CDPS permits that are issued prior to the effective date of anticipated changes to the chronic arsenic standard in the 2016 Basic Standards Rulemaking to not have the temporary modification expire within the term of a permit. The Commission adopted this temporary modification to allow time for the Division, dischargers and stakeholders to continue a workgroup process to resolve the uncertainty regarding the appropriateness of the W+F chronic arsenic standard of 0.02 μg/L with respect to a technologically feasible level of treatment. 
For new or increased discharges that commence on or after 6/1/2013, the temporary modification adopted is As(ch) = 0.02–3.0 μg/L (Trec), expiring on 12/31/2021. The Commission decided that since the technologically achievable arsenic level is less stringent than the calculated W+F criterion, the temporary modification for new or increased discharges will be a range of 0.02-3.0 μg/L. The first number in the range is the health-based value, based on the Commission’s established methodology for human health-based standards that protect against the combined exposure of drinking water and eating fish. The second number in the range is the Commission’s initial determination of a technologically achievable value for arsenic, set at 3.0 μg/L. Control requirements, such as discharge permits effluent limitations, shall be established using the first number in the range as the ambient water quality target, provided that no effluent limitation shall require an “end of pipe” discharge level more restrictive than the second number in the range during the effective period for this temporary modification. The expiration date of the temporary modification was set at 12/31/21 to allow for CDPS permits that are issued prior to the effective date of anticipated changes to the chronic arsenic standard in the 2016 Basic Standards Rulemaking to not have the temporary modification expire within the term of a permit. The Commission adopted this temporary modification to allow time for the Division, dischargers and stakeholders to continue a workgroup process to resolve the uncertainty regarding the appropriateness of the W+F chronic arsenic standard of 0.02 μg/L with respect to a technologically feasible level of treatment. 
The technologically feasible level of 3.0 μg/L for arsenic is based upon testimony heard by the Commission at the December 13, 2011 Emergency Revisions to Regulation #38. At the December 13, 2011 hearing, the Commission determined, as a practical manner, that 3.0 μg/L is the lowest level that is technologically achievable for common types of water treatment facilities. At the April 8, 2013 Rulemaking, the Commission heard testimony that concurred with the finding from December 13, 2011 that an initial reasonable  lower limit of treatment technology for arsenic is 3.0 μg/L, pending further investigation by the Division, dischargers and stakeholders. The Division intends to address the uncertainty of the W+F chronic arsenic standard with respect to a technologically feasible level of treatment through a continued workgroup process, and propose a revised W+F chronic arsenic standards as part of the 2016 Basic Standards Rulemaking Hearing
Temporary modifications were adopted on the following segments. The segments identified have the previously adopted W+F chronic arsenic standard of 0.02 μg/L and an identified CDPS permit or permits that discharge immediately to or directly above the identified segment. 
Rio Grande 1
Rio Grande 2
Rio Grande 4
Rio Grande 5
Rio Grande 9
Rio Grande 11
Rio Grande 14
Rio Grande 19
Rio Grande 21
Rio Grande 28
Rio Grande 30
Alamosa River, La Jara Creek, Conejos River 13
Alamosa River, La Jara Creek, Conejos River 14
Alamosa River, La Jara Creek, Conejos River 15
Alamosa River, La Jara Creek, Conejos River 17
Alamosa River, La Jara Creek, Conejos River 20
Closed Basin – San Luis Valley 4
Closed Basin – San Luis Valley 9b
Closed Basin – San Luis Valley 11
Closed Basin – San Luis Valley 12
PARTIES TO THE RULEMAKING HEARING
1.	Colorado Mining Association
2.	Union Gold, Inc.
3.	Colorado Department of Transportation
4.	City of Colorado Springs and Colorado Springs Utilities
5.	Town of Crested Butte
6.	Mountain Coal Company
7.	Centennial Water and Sanitation District
8.	MillerCoors, LLC
9.	Plum Creek Wastewater Authority
10.	Tri-State Generation & Transmission Association
11.	Climax Molybdenum Company
12.	Littleton/Englewood Wastewater Treatment Plant
13.	Eagle River Water and Sanitation District
14.	City of Boulder
15.	City and County of Denver
16.	Parker Water and Sanitation District
17.	U.S. Energy Corp.
18.	U.S. Environmental Protection Agency
19.	City of Greeley