COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT
WATER QUALITY CONTROL COMMISSION 
REGULATION NO. 31 
THE BASIC STANDARDS AND METHODOLOGIES FOR SURFACE WATER 
(5 CCR 1002-31)
. . . 
31.11	BASIC STANDARDS APPLICABLE TO SURFACE WATERS OF THE STATE
. . .
(3)	The interim organic pollutant standards contained in the following Basic Standards for Organic Chemicals Table are applicable to all surface waters of the state for which the corresponding use classifications have been adopted, unless alternative site-specific standards have been adopted pursuant to sub-section (4) below.

BASIC STANDARDS FOR ORGANIC CHEMICALS
(in micrograms per liter)
	
Parameter		Human Health Based1	Aquatic Life Based4  	
	CAS No.	Water Supply2	Water+Fish3	
Fish Ingestion8	Acute	Chronic	

Acenaphthene	83-32-9	
420	
420	
---10	
1,700	
520	
Acetochlor	34256-82-1	140	---	---	---	---	

Acrolein	107-02-8	
3.5	
3.5	
9.3	
68	
21	

AcrylamideC	79-06-1	
0.0078	---	---	---	---	

AcrylonitrileC	107-13-1	
0.065	
0.051	
0.25	
7,500	
2,600	

Alachlor	15972-60-8	
2M	
2	
140	
---	
---	

Aldicarb	116-06-3	
7M	
---	
---	
---	
---	

Aldicarb Sulfone	1646-88-4	
7M	
---	
---	
---	
---	

Aldicarb Sulfoxide	1646-87-3	
7M	---	
---	
---	
---	

AldrinC	309-00-2	
0.0021	
4.9X10-5	
5.0X10-5	
1.5	
---	

AnilineC	62-53-3	6.1	---	---	---	
---	

Anthracene (PAH)	  120-12-7	
2,100	
2,100	
40,000	
---	
---	

AramiteC	140-57-8	1.4	---	
---	
---	
---	

Atrazine	1912-24-9	
3M	
---	
---	
---	
---	

AzobenzeneC	103-33-3	
0.32	
---	
---	
---	
---	

BenzeneC, 12	71-43-2	
2.3 to 5M	
2.2	
51	
5,300	
---	

BenzidineC	92-87-5	
0.00015	
8.6X10-5	
0.00020	
2,500	
---	

Benzo(a)anthracene (PAH)C	56-55-3	
0.0048	
0.0038	
0.018	
---	
---	

Benzo(a)pyrene (PAH)C, 12	50-32-8	
0.0048 to 
0.2M	
0.0038	
0.018	
---	
---	

Benzo(b)fluoranthene (PAH)C	205-99-2	
0.0048	
0.0038	
0.018	
---	
---	

Benzo(k)fluoranthene (PAH)C	207-08-9	
0.0048	
0.0038	
0.018	
---	
---	

Benzo(g,h,i)perylene (PAH)	191-24-2	
---	
0.0038	
0.018	
---	
---	

BenzotrichlorideC	98-07-7	
0.0027	---	
---	
---	
---	

Benzyl chlorideC	100-44-7	
0.21	---	---	---	
---	

Bis(chloromethyl)ether (BCME)C	542-88-1	0.00016	0.0001	0.0003	
---	
---	

BromateC	15541-45-4	0.050	
---	
---	
---	
---	

Bromodichloromethane (HM)C	75-27-4	
---	
0.55	
17	
11,000	
---	

Bromoform (HM)C	75-25-2	
---	
4.3	
140	
---	
---	

Butyl benzyl phthalate	85-68-7	
1,400	
1,400	
1,900	
---	
---	

CarbofuranC, 12	1563-66-2	
35 to 
40 M	
---	
---	
---	
---	

Carbon tetrachlorideC, 12	56-23-5	
0.27 to 
5M	
0.23	
1.6	
35,200	
---	

ChlordaneC, 12	57-74-9	
0.10 to
2M	
0.00080	
0.00081	
1.2	
0.0043	

Chlorethyl ether (BIS-2)C	111-44-4	
0.032	
0.030	
0.53	
---	
---	

Chlorobenzene11	108-90-7	
100 M	
100	
1,600	
---	
---	

Chlorodibromomethane (HM)11	124-48-1	
---	
54.0	
1,700	
---	
---	

Chloroform (HM)C	67-66-3	
---	
3.4	
110	
28,900	
1,240	

Chloroisopropyl ether(BIS-2)	108-60-1	
280	
280	
65,000	
---	
---	

4-Chloro-3-methylphenol	59-50-7	
210	
---	
---	
30	
---	

Chloronapthalene	91-58-7	
560	
560	
---10	
2,300	
620	

Chlorophenol,2-	95-57-8	
35	
35	
150	
4,380	
2,000	

Chlorphrifos	2921-88-2	
21	
---	
---	
0.083	
0.041	

Chrysene (PAH)C	218-01-9	
0.0048	
0.0038	
0.018	
---	
---	

DDDC	72-54-8	
0.15	
0.00031	
0.00031	
0.6	
---	

DDEC	72-55-9	
0.1	
0.00022	
0.00022	
1,050	
---	
DDTC	50-29-3	0.1	
0.00022	0.00022	0.55	0.001	

Dalapon	75-99-0	200M	
---	---	
---	
---	

Demeton	8065-48-3	---	---	---	
---	0.1	
Diazinon	333-41-5	---	---	---	0.17	0.17	

Dibenzo(a,h)anthracene (PAH)C	53-70-3	0.0048	0.0038	0.018	
---	
---	

1,2 Dibromo-3-Chloropropane (DBCP)C	96-12-8	
0.2M	
---	---	
---	
---	
Dicamba	1918-00-9	210	170	860	---	---	

Dichloroacetic acidC	79-43-6	0.7	---	---	---	---	

Dichlorobenzene 1,211	95-50-1	
600M	
420	
1,300	
---	
---	

Dichlorobenzene 1,3	541-73-1	
94	
94	
960	
---	
---	

Dichlorobenzene 1,411	106-46-7	
75M	
63	
190	
---	
---	

DichlorobenzidineC	91-94-1	
0.078	
0.021	
0.028	
---	
---	

Dichloroethane 1,2C, 12	107-06-2	
0.38 to
5M	
0.38	
37	
118,000	
20,000	

Dichloroethylene 1,1	75-35-4	
7M	
7	
3,600	
---	
---	

Dichloroethylene 1,2-cis	156-59-2	
70M	
---	
---	
---	
---	

Dichloroethylene 1,2-trans11	156-60-5	
100M	
100	
10,000	
---	
---	

Dichlorophenol 2,4	120-83-2	
21	
21	
290	
2,020	
365	

Dichlorophenoxyacetic acid (2,4-D)	94-75-7	
70M	
---	
---	
---	
---	

Dichloropropane 1,2C, 12	78-87-5	
0.52 to 
5M	
0.50	
14	
23,000	
5,700	

Dichloropropylene 1,3C	542-75-6	
0.35	
0.34	
21	
6,060	
244	

DichlorvosC	62-73-7	
0.12	
---	---	---	---	

DieldrinC	60-57-1	
0.002	
5.2X10-5	
5.4X10-5	
0.24	
0.056	

Diethyl phthalate	84-66-2	
5,600	
5,600	
44,000	
---	
---	

Diisopropylmethylphosphonate (DIMP)	1445-75-6	
8	

---	
---	
---	
---	
Dimethylphenol 2,4	105-67-9	140	140	850	2,120	---	

Dimethyl phthalate	131-11-3	
70,000	
70,000	
1,100,000	
---	
---	

Di-n-butyl phthalate	84-74-2	
700	
700	
4,500	
---	
---	

Dinitrophenol 2,4	51-28-5	
14	
14	
5,300	
---	
---	
Dinitro-o-cresol 4,6	534-52-1	0.27	1.3	28	---	---	

Dinitrotoluene 2,4C	121-14-2	
0.11	
0.11	
3.4	
---	
---	

Dinitrotoluene 2,6C	606-20-2	
---	
---	
---	
330	
230	

Dinoseb	88-85-7	
7M	
---	
---	
---	
---	

Dioxane 1,4-	123-91-1	6.1(effective through 3/21/2010)	
---	
---	
---	
---	

Dioxane 1,4-	123-91-1	3.2(effective 3/22/2010)	
---	
---	
---	
---	

Dioxin (2,3,7,8 TCDD)C, 12	1746-01-6	
2.2x10-7 
to 3.0x10-5, M	
5.0X10-9	
5.1X10-9	
0.01	
0.00001	

Diphenylhydrazine 1,2C	122-66-7	
0.044	
0.036	
0.20	
270	
---	

Di(2-ethylhexyl)adipate	103-23-1	
400M	
---	
---	
---	
---	

Diquat12	85-00-7	
15 to 
20M	
---	
---	
---	
---	

Endosulfan	115-29-7	
42	
---10	
---	
0.11	
0.056	

Endosulfan, alpha	959-98-8	
42	
---10	
---	
0.11	
0.056	

Endosulfan, beta	33213-65-9	
42	
---10	
---	
0.11	
0.056	

Endosulfan sulfate	1031-07-8	
42	
---10	
---	
0.11	
0.056	

Endothall	145-73-3	
100M	
---	
---	
---	
---	

Endrin	72-20-8	
2M	
----10	
---	
0.086	
0.036	

Endrin aldehyde	7421-93-4	
2.1	
0.29	
0.30	
---	
---	

EpichlorohydrinC	106-89-8	3.5	
---	
---	
---	
---	
Ethylbenzene11	100-41-4	700M	530	2,100	32,000	---	

Ethylene dibromideC, 12
(1,2 – dibromoethane)	106-93-4	
0.02 to  
0.05M	
---	
---	
---	
---	

Ethylhexyl phthalate 
(BIS-2)C, 12(DEHP)	117-81-7	
2.5 to
6M	
1.2	
2.2	
---	
---	

Fluoranthene (PAH)	206-44-0	
280	
130	
140	
3,980	
---	

Fluorene (PAH)	86-73-7	
280	
1,100	
5,300	
---	
---	
FolpetC	133-07-3	10	---	---	---	---	
FurmecycloxC	60568-05-0	1.2	---	---	---	---	
Glyphosate	1071-83-6	700M	---	---	---	---	
Guthion	86-50-0	---	---	---	---	0.01	

HeptachlorC, 12	76-44-8	
0.008 to 
0.4M	
7.8X10-5	
7.9X10-5	
0.52	
0.0038	

Heptachlor epoxideC, 12	1024-57-3	
0.004 to 
0.2M	
3.9X10-5	
3.9X10-5	
0.52	
0.0038	

HexachlorobenzeneC, 12	118-74-1	
0.022 to 
1.0M	
0.00028	
0.00029	
---	
---	

Hexachlorobutadiene	87-68-3	
0.45	
0.44	
---10	
90	
9.3	

Hexachlorocyclohexane,
AlphaC	319-84-6	
0.0056	
0.0026	
0.0049	
---	
---	

Hexachlorocyclohexane,
Beta	319-85-7	
0.019	
0.0091	
0.017	
---	
---	

Hexachlorocyclohexane, Gamma (Lindane)	58-89-9	
0.2M	
0.2	
---10	
0.95	
0.08	

Hexachlorocyclohexane, TechnicalC	608-73-1	
---	
0.012	
0.041	
100	
---	

Hexachlorocyclopentadiene11, 12
(HCCPD)	77-47-4	
42 to 
50M	
40	
---10	
7	
5	

Hexachlorodibenzo-p-dioxin (1,2,3,7,8,9-hcdd)C	19408-74-3	
5.60E-06	---	---	---	---	

Hexachloroethane11	67-72-1	
0.7	
0.4	
0.92	
980	
540	

Hydrazine/Hydrazine sulfateC	302-01-2	
0.012	---	---	
---	
---	

Indeno(1,2,3-cd)pyrene (PAH)C	193-39-5	
0.0048	
0.0038	
0.018	
---	
---	

Isophorone11	78-59-1	
140	
130	
3,600	
---	
---	
Malathion	121-75-5	140	---	---	---	0.1	

Methoxychlor12	72-43-5	
35 to
40M	
---10	
---	
---	
0.03	

Methyl bromide (HM)	74-83-9	
---	
9.8	
1,500	
---	
---	

Methyl chloride (HM)C	74-87-3	
---	
5.6	
180	
---	
---	

4,4-Methylene bis (N,N’-dimethyl)anilineC	101-61-1	
0.76	
---	---	---	
---	

Methylene chlorideC, 12	75-09-2	
4.7 to
5M	
4.6	
590	
---	
---	
Metribuzin	21087-64-9	180	160	1,700	---	---	

Mirex	2385-85-5	
1.4	
---	
---	
---	
0.001	
Naphthalene (PAH)	91-20-3	140	140	---10	2,300	620	

Nitrobenzene	98-95-3	
3.5	
3.5	
690	
27,000	
---	

Nitrophenol 4	100-02-7	
56	
56	
9,700	
---	
---	

Nitrosodibutylamine NC	924-16-3	
0.0065	
0.0043	
0.012	
---	
---	

Nitrosodiethylamine NC	55-18-5	
0.00023	
0.00023	
0.0083	
---	
---	

Nitrosodimethylamine NC	62-75-9	
0.00069	
0.00069	
3.0	
---	
---	

N-NitrosodiethanolamineC	1116-54-7	0.013	---	---	---	
---	

Nitrosodiphenylamine NC	86-30-6	
7.1	
3.3	
6.0	
---	
---	

N-Nitroso-N-methylethylamineC	10595-95-6	0.0016	---	---	---	
---	

Nitrosopyrrolidine NC	930-55-2	
0.017	
0.016	
36	
---	
---	

N-Nitrosodi-n-propylamineC	621-64-7	0.005	
0.005	
0.50	
---	
---	
Nonylphenol	84852‑15‑3 and 25154‑52‑3	---	---	---	28
(effective 7/1/2010)	6.6
(effective 7/1/2010)	

Oxamyl (vydate)12	23135-22-0	
175 to
200M	
---	
---	
---	
---	

PCBsC, 9, 12	1336-36-3	
0.0175 to
0.5M	
6.4X10-5	
6.4X10-5	
2.0	
0.014	

Parathion	56-38-2	
---	
---	
---	
0.065	
0.013	

Pentachlorobenzene	608-93-5	
5.6	
1.4	
1.5	
---	
---	

PentachlorophenolC, 12	87-86-5	
0.29 to
1.0M 	
0.27	
3.0	
196	
156	

Phenol	108-95-2	
2,100	
2,100	
---10	
10,200	
2,560	

Picloram	1918-02-1	
490	
---	
---	
---	
---	
Prometon	1610-18-0	100	---	---	---	---	
Propylene oxideC	75-56-9	
0.15	---	---	
---	
---	
Pyrene (PAH)	129-00-0	
210	
210	
4,000	
---	
---	

QuinolineC	91-22-5	0.012	
---	
---	
---	
---	

Simazine	122-34-9	
4M	
---	
---	
---	
---	

Styrene	100-42-5	
100M	
---	
---	
---	
---	

Tetrachlorobenzene 1,2,4,5-
  	95-94-3	
2.1	
0.97	
1.07	
---	
---	

Tetrachloroethane 1,1,2,2C	79-34-5	
0.18	
0.17	
4	
---	
2,400	

Tetrachloroethylene
(PCE)	127-18-4	
5M	
0.69	
3.3	
5,280	
840	

Toluene11, 12	108-88-3	
560 to 1,000M	
510	
5,900	
17,500	
---	

ToxapheneC, 12	8001-35-2	
0.032 to
3M	
0.00028	
---10	
0.73	
0.0002	
Tributyltin (TBT)	56573-85-4 	---	---	---	0.46	0.072 	

Trichlorobenzene 1,2,4-11	120-82-1	
70M	
35	
---10	
250	
50	

Trichloroethane 1,1,1
(1,1,1-TCA)	71-55-6	
200M	
---	
---	
---	
---	

Trichloroethane 1,1,2
(1,1,2-TCA)11, 12	79-00-5	
2.8
to 5M 	
2.7	
71	
9,400	
---	

Trichloroethylene (TCE)	79-01-6	
5M	
2.5	
30	
45,000	
21,900	
Trichlorophenol 2,4,5	95-95-4	700	700	3,600	---	---	

Trichlorophenol 2,4,6C	88-06-2	
3.2	
1.4	
2.4	
---	
970	

Trichlorophenoxypropionic acid (2,4,5-tp) (Silvex)	93-72-1	
50M	
---	
---	
---	
---	

Trihalomethanes	(total)7	
80	
80	
---	
---	
---	

Vinyl ChlorideC, 12	75-01-4	
0.023 to 2M 	
0.023	
2.3	
---	
---	
Xylenes (total)12	1330-20-7	1,400 to 10,000M	---	---	---	---	

1 	All standards are chronic or 30-day standards.  They are based on information contained in EPA's Integrated Risk Information System (IRIS) and/or EPA lifetime health advisories for drinking water using a 10-6 incremental risk factor unless otherwise noted.
2	Only applicable to segments classified for water supply.
3 	Applicable to all Class 1 aquatic life segments which also have a water supply classification or Class 2 aquatic life segments which also have a water supply classification designated by the Commission after rulemaking hearing.  These class 2 segments will generally be those where fish of a catchable size and which are normally consumed are present, and where there is evidence that fishing takes place on a recurring basis.  The Commission may also consider additional evidence that may be relevant to a determination whether the conditions applicable to a particular segment are similar enough to the assumptions underlying the water plus fish ingestion criteria to warrant the adoption of water plus fish ingestion standards for the segment in question.
4 	Applicable to all aquatic life segments.
5	PQL's for the constituents listed above can be found at section 61.8((2)(I) of the Regulations for the State Discharge Permit System.
6	Standards are pH dependent.  Those listed are calculated for pH = 7.8.
	     Acute = e[1.005(pH)-4.869];  Chronic = e[1.005(pH)-5.134].
7	Total trihalomethanes are considered the sum of the concentrations of bromodichloromethane (CAS No. 75-27-4), dibromochloromethane (Chlorodibromomethane(HM), CAS No. 124-48-1), tribromomethane (bromoform, CAS No. 75-25-2) and trichloromethane (chloroform, CAS No. 67-66-3).
8	Applicable to the following segments which do not have a water supply classification: all Class 1 aquatic life segments or Class 2 aquatic life segments designated by the Commission after rulemaking hearing.  These class 2 segments will generally be those where fish of a catchable size and which are normally consumed are present, and where there is evidence that fishing takes place on a recurring basis.  The Commission may also consider additional evidence that may be relevant to a determination whether the conditions applicable to a particular segment are similar enough to the assumptions underlying the fish ingestion criteria to warrant the adoption of fish ingestion standards for the segment in question.
9	PCBs are a class of chemicals which include aroclors, 1242, 1254, 1221, 1232, 1248,1260 and 1016, CAS numbers 53469-21-9, 11097-69-1, 11104-28-2, 11141-16-5, 12672-29-6, 11096-82-5, and 12674-11-2 respectively.  The aquatic life criteria apply to this set of PCBs.  The human health criteria apply to total PCBs, i.e. the sum of all congenor or all isomer analyses.
10	The chronic aquatic life standard is more stringent than the associated Water+Fish or Fish Ingestion standard, and therefore no Water+Fish or Fish Ingestion standard has been adopted.
11	The Water+Fish and Fish Ingestions standards for these compounds have been calculated using a relative source contribution (RSC).
12	Whenever a range of standards is listed and referenced to this footnote, the first number in the range is a strictly health-based value, based on the Commission’s established methodology for human health-based standards.  The second number in the range is a maximum contaminant level, established under the federal Safe Drinking Water Act that has been determined to be an acceptable level of this chemical in public water supplies, taking treatability and laboratory detection limits into account.  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.  Water bodies will be considered in attainment of this standard, and not included on the Section 303(d) List, so long as the existing ambient quality does not exceed the second number in the range.
C	Carcinogens classified by the EPA as A, B1, or B2.
M	Drinking water MCL.
CAS No. - Chemical Abstracts Service Registry Number.
(HM) – Halomethanes
(PAH) - Polynuclear Aromatic Hydrocarbons. 
. . .
31.46	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE; DECEMBER 10, 2007 RULEMAKING; EFFECTIVE MAY 31, 2008
The provisions of sections 25-8-202(1)(b), 25-8-204; and 25-8-402, C.R.S., provide the specific statutory authority for adoption.  The Commission also adopted, in compliance with section 24-4-103(4) C.R.S., the following statement of basis and purpose.
BASIS AND PURPOSE:
In this rulemaking, the Commission adopted revised and new organic chemical standards in section 31.11(3).  In an effort to keep ground water and surface water organic chemical standards consistent, the changes to 31.11(3) were considered during the same hearing that addressed changes to the statewide Ground Water Organic Chemical Standards in Regulation No. 41 (Basic Standards for Ground Water).  
In adopting these new and revised organic chemical standards, the Commission continued to rely on its past policy decisions and precedence documented in Commission Policy 96-2.  Additionally, as per Departmental policy the Commission has relied on the United States Environmental Protection Agency’s (EPA) Integrated Risk Information System (IRIS) as its first tier source of toxicological data.  Review of the IRIS data that had been updated since the last revisions to section 31.11(3) indicated that the water quality standards for two organic chemicals, toluene and 1,2-dibromoethane, needed to be revised.  
At the last hearing addressing section 31.11(3), in September 2004, during which the Commission adopted water quality standards for several carcinogenic compounds, EPA had requested that a future rulemaking consider water quality standards for non-carcinogenic compounds.  For this hearing the Commission reviewed several non-carcinogenic compounds that lacked water quality standards.  This review identified four pesticides for which the Commission elected to adopt water quality standards: acetochlor, dicamba, metribuzin, and prometon.  Aquatic life-based standards for diazinon were also adopted, based on EPA guidance. 
Nonylphenol:  The Commission considered evidence presented in regards to the proposal to adopt aquatic life-based standards for nonylphenol.  The Commission decided to adopt acute and chronic standards with a delayed effect date of 7/1/2010 as agreed to by the parties and the Division.  This delay is intended to allow time for EPA, the Division and the parties to resolve uncertainty regarding the analytical methods for testing influent waste streams.  Prior to the effective date, the Metro Wastewater Reclamation District, the City of Boulder, Littleton/Englewood and Colorado Springs Utilities have committed to working on source control of nonlyphenol with the commercial laundry sector through their Pretreatment Programs.  For purposes of discharge permits, the Commission expects that, because of limitations in the available data, the Division will include effluent monitoring requirements in major permits issued prior to the delayed effective date.  The monitoring requirement would become effective the same date that the standards became effective.
The Commission also corrected several typographical errors and added common synonyms for some of the organic chemicals.  
PARTIES TO THE RULEMAKING
1.	Centennial Water and Sanitation District, Town of Castle Rock, Castle Pines Metropolitan District, Consolidated Mutual Water Company, Rangeview Metropolitan District
2.	Metro Wastewater Reclamation District
3.	Colorado Wastewater Utility Council
4.	City of Boulder
5.	City of Colorado Springs and Colorado Springs Utilities
6.	City and County of Denver Department of Environmental Health
7.	Climax Molybdenum Company
8.	Information Network for Responsible Mining (INFORM), High Country Citizens’ Alliance (HCCA), and Coloradoans Against Resource Destruction (CARD)
9.	United States Environmental Protection Agency, Region 8
10.	U.S. Department of Energy (DOE) Office of Legacy Management
11.	Upper Black Squirrel Creek Ground Water Management District