The water quality standards specified in subsection B below are deemed necessary and appropriate to protect groundwater uses as specified in section 41.4 , and shall be adopted to protect such classified uses. The standards specified in subsections A and C apply to all State groundwaters, unless alternative site-specific standards have been adopted for a specified area pursuant to subsection D below.
"Agricultural Use - Quality"
"Surface Water Quality Protection"
"Potentially Usable Quality"
Radioactive Materials Standards1
Parameter | Standard |
Americium2 | 0.15 pCi/l |
Cesium 134 | 80 pCi/l |
Plutonium 2392, and 2402 | 0.15 pCi/l |
Radium 2262 and 2282 | 5 pCi/l |
Strontium 902 | 8 pCi/l |
Thorium 2302 and 2322 | 60 pCi/l |
Tritium | 20,000 pCi/l |
pCi/l = Picocuries Per Liter
1 In site-specific cases, when it has been demonstrated that there are negligible differences between the results of dissolved (filtered) samples and total (unfiltered) samples, then dissolved results may be utilized for implementing the radioactive material standards.
2 Radionuclide samples for these materials should be analyzed using unfiltered (total) samples.
Note that all standards in table A are being adopted as "interim standards." These interim standards will remain in effect until alternative permanent standards are adopted by the Commission in revisions to this regulation or site-specific standards determinations. Although fully effective with respect to current regulatory applications, these interim standards shall not be considered final or permanent standards subject to restrictions such as antibacksliding or downgrading.
TABLE A GROUNDWATER ORGANIC CHEMICAL STANDARDS (in micrograms per liter) | ||
Parameter | CAS No. | STANDARD1 |
Acenaphthene | 83-32-9 | 420 |
Acetochlor | 34256-82-1 | 140 |
Acetone | 67-64-1 | 6300 |
Acrolein | 107-02-8 | 3.5 |
AcrylamideC, 8 | 79-06-1 | 0.022 |
AcrylonitrileC | 107-13-1 | 0.065 |
Alachlor | 15972-60-8 | 2.0M |
Aldicarb | 116-06-3 | 7.0M |
Aldicarb Sulfone | 1646-88-4 | 7.0M |
Aldicarb Sulfoxide | 1646-87-3 | 7.0M |
AldrinC | 309-00-2 | 0.0021 |
AnilineC | 62-53-3 | 6.1 |
Anthracene (PAH) | 120-12-7 | 2100 |
AramiteC | 140-57-8 | 1.4 |
Atrazine | 1912-24-9 | 3.0M |
AzobenzeneC | 103-33-3 | 0.32 |
BenzeneC, 2 | 71-43-2 | 5.0M |
BenzidineC | 92-87-5 | 0.00015 |
Benzo(a)anthracene (PAH)C, 8 | 56-55-3 | 0.16 |
Benzo(a)pyrene (PAH)C, 8 | 50-32-8 | 0.016 |
Benzo(b)fluoranthene (PAH)C, 8 | 205-99-2 | 0.16 |
Benzo(k)fluoranthene (PAH)C, 8 | 207-08-9 | 1.6 |
BenzotrichlorideC | 98-07-7 | 0.0027 |
Benzyl chlorideC | 100-44-7 | 0.21 |
Bis(chloromethyl)ether (BCME)C | 542-88-1 | 0.00016 |
BiphenylC | 92-52-4 | 4.4 |
BromateC | 15541-45-4 | 0.05 |
Bromobenzene | 108-86-1 | 56 |
Bromodichloromethane (THM)C, 7 | 75-27-4 | 0.56 |
Bromoform (THM)C, 7 | 75-25-2 | 4 |
Butyl benzyl phthalate | 85-68-7 | 1,400 |
Carbofuran6 | 1563-66-2 | 35 to 40M |
Carbon tetrachlorideC, 6 | 56-23-5 | 0.5 to 5M |
ChlordaneC, 6 | 57-74-9 | 0.10 to 2M |
Chlordecone C | 143-50-0 | .0035 |
Chlorethyl ether (BIS-2)C | 111-44-4 | 0.032 |
Chlorobenzene | 108-90-7 | 100M |
Chloroform (THM)C, 7 | 67-66-3 | 3.5 |
Chloroisopropyl ether (BIS-2) | 108-60-1 | 280 |
4-Chloro-3-methylphenol | 59-50-7 | 210 |
Chloronaphthalene | 91-58-7 | 560 |
Chlorophenol, 2- | 95-57-8 | 35 |
Chlorpyrifos | 2921-88-2 | 21 |
Chrysene (PAH)C, 8 | 218-01-9 | 16 |
Dalapon | 75-99-0 | 200M |
DDDC | 72-54-8 | 0.15 |
DDEC | 72-55-9 | 0.1 |
DDTC | 50-29-3 | 0.1 |
Di(2-ethylhexyl)adipate | 103-23-1 | 400M |
Dibenzo(a,h)anthracene (PAH)C, 8 | 53-70-3 | 0.016 |
1,2-Dibromo-3-Chloropropane (DBCP) | 96-12-8 | 0.2M |
Dibromochloromethane (chlorodibromomethane) (THM)3a, 7 | 124-48-1 | 14 |
Dibromoethane 1,2C | 106-93-4 | 0.018 |
Dicamba | 1918-00-9 | 210 |
Dichloroacetic acidC | 79-43-6 | 0.7 |
Dichlorobenzene 1,2 | 95-50-1 | 600M |
Dichlorobenzene 1,3 | 541-73-1 | 94 |
Dichlorobenzene 1,4 | 106-46-7 | 75M |
DichlorobenzidineC | 91-94-1 | 0.078 |
Dichloroethane 1,2C, 6 | 107-06-2 | 0.38 to 5M |
Dichloroethylene 1,1 | 75-35-4 | 7M |
Dichloroethylene 1,2-cis6 | 156-59-2 | 14 to 70M |
Dichloroethylene 1,2-trans6 | 156-60-5 | 140 or 100M |
Dichloromethane (methylene chloride) C, 6, 8 | 75-09-2 | 5.6 or 5M |
Dichlorophenol 2,4 | 120-83-2 | 21 |
Dichlorophenoxyacetic acid (2,4-D) | 94-75-7 | 70M |
Dichloropropane 1,2C, 6 | 78-87-5 | 0.52 to 5M |
DichlorvosC | 62-73-7 | 0.12 |
DieldrinC | 60-57-1 | 0.002 |
Diethyl phthalate | 84-66-2 | 5,600 |
Diisopropylmethylphosphonate (DIMP)4 | 1445-75-6 | 8 |
Dimethylphenol 2,4 | 105-67-9 | 140 |
Di-n-butyl phthalate | 84-74-2 | 700 |
Dinitro-o-cresol 4,6 | 534-52-1 | 0.27 |
Dinitrophenol 2,4 | 51-28-5 | 14 |
Dinitrotoluene 2,4C | 121-14-2 | 0.11 |
Dinoseb | 88-85-7 | 7M |
Dioxane 1,4-C | 123-91-1 | 0.35 |
Dioxin (2,3,7,8 TCDD)C, 6 | 1746-01-6 | 2.2x10-7 to 3.0x10-5, M |
Diphenylhydrazine 1,2C | 122-66-7 | 0.044 |
Diquat6 | 85-00-7 | 15 to 20M |
Endosulfan | 115-29-7 | 42 |
Endosulfan, alpha | 959-98-8 | 42 |
Endosulfan, beta | 33213-65-9 | 42 |
Endosulfan sulfate | 1031-07-8 | 42 |
Endothall | 145-73-3 | 100M |
Endrin | 72-20-8 | 2M |
Endrin aldehyde | 7421-93-4 | 2.1 |
EpichlorohydrinC | 106-89-8 | 3.5 |
Ethylbenzene | 100-41-4 | 700M |
Ethylene DibromideC, 6 (1,2-dibromoehtane) | 106-93-4 | 0.02 to 0.05M |
Ethylene glycol monobutyl ether (EGBE) (2-Butoxyethanol) | 111-76-2 | 700 |
Ethylhexyl phthalate (BIS-2)C, 6 (DEHP) | 117-81-7 | 2.5 to 6M |
Fluoranthene (PAH) | 206-44-0 | 280 |
Fluorene (PAH) | 86-73-7 | 280 |
FolpetC | 133-07-3 | 10 |
FurmecycloxC | 60568-05-0 | 1.2 |
Glyphosate | 1071-83-6 | 700M |
HeptachlorC, 6 | 76-44-8 | 0.008 to 0.4M |
Heptachlor epoxideC, 6 | 1024-57-3 | 0.004 to 0.2M |
HexachlorobenzeneC, 6 | 118-74-1 | 0.022 to 1.0M |
Hexachlorobutadiene | 87-68-3 | 0.45 |
Hexachlorocyclohexane, AlphaC | 319-84-6 | 0.0056 |
Hexachlorocyclohexane, Gamma (Lindane) | 58-89-9 | 0.2M |
Hexachlorocyclopentadiene6 (HCCPD) | 77-47-4 | 42 to 50M |
Hexachlorodibenzo-p-dioxin (1,2,3,7,8,9-hcdd)C | 19408-74-3 | 5.60E-06 |
HexachloroethaneC | 67-72-1 | 0.88 |
Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX)3b | 121-82-4 | 0.42 |
Hexanone 2 | 591-78-6 | 35 |
Hydrazine/Hydrazine sulfateC | 302-01-2 | 0.012 |
Indeno (1,2,3-cd) pyrene (PAH)C | 193-39-5 | 0.16 |
Isophorone3 | 78-59-1 | 140 |
Malathion | 121-75-5 | 140 |
Methanol | 67-56-1 | 14,000 |
Methoxychlor6 | 72-43-5 | 35 to 40M |
Methylene bis(N,N'-dimethyl)aniline 4,4'C | 101-61-1 | 0.76 |
Metribuzin | 21087-64-9 | 180 |
Mirex | 2385-85-5 | 1.4 |
Naphthalene (PAH) | 91-20-3 | 140 |
Nitrobenzene | 98-95-3 | 14 |
Nitrophenol 4 | 100-02-7 | 56 |
Nitrosodimethylamine NC(NDMA) | 62-75-9 | 0.00069 |
N-NitrosodiethanolamineC | 1116-54-7 | 0.013 |
Nitrosodiphenylamine NC | 86-30-6 | 7.1 |
N-Nitrosodi-n-propylamineC | 621-64-7 | 0.005 |
N-Nitroso-N-MethylethylamineC | 10595-95-6 | 0.0016 |
Oxamyl (vydate)6 | 23135-22-0 | 175 to 200M |
PCBsC, 5, 6 | 1336-36-3 | 0.0175 to 0.5M |
Pentachlorobenzene | 608-93-5 | 5.6 |
PentachlorophenolC, 6 | 87-86-5 | 0.088 to 1.0M |
Perchlorate | 7790-98-9 | 4.9 |
Phenol | 108-95-2 | 2,100 |
Picloram | 1918-02-1 | 490 |
Prometon | 1610-18-0 | 100 |
Propylene oxideC | 75-56-9 | 0.15 |
Pyrene (PAH) | 129-00-0 | 210 |
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 |
Tetrachloroethane 1,1,2,2C | 79-34-5 | 0.18 |
Tetrachloroethylene (PCE)C, 6 | 127-18-4 | 17 or 5M |
Tetrahydrofuran | 109-99-9 | 6,300 |
Toluene6 | 108-88-3 | 560 to 1,000M |
Total Trihalomethanes (TTHMs)7 | N/A | 80M |
ToxapheneC, 6 | 8001-35-2 | 0.032 to 3M |
Trichloroacetic acidC | 76-03-9 | 0.52 |
Trichlorobenzene 1,2,4 | 120-82-1 | 70M |
Trichloroethane 1,1,1 (1,1,1-TCA)6 | 71-55-6 | 14,000 or 200M |
Trichloroethane 1,1,23a, 6 (1,1,2-TCA) | 79-00-5 | 2.8 to 5M |
Trichloroethylene (TCE) | 79-01-6 | 5M |
Trichloropropane 1,2,3C, 8 | 96-18-4 | 3.7E-4 |
Trichlorophenol 2,4,5 | 95-95-4 | 700 |
Trichlorophenol 2,4,6C | 88-06-2 | 3.2 |
Trichlorophenoxyproprionic acid (2,4,5-tp) (Silvex) | 93-72-1 | 50M |
Trimethylbenzene 1,2,3 | 526-73-8 | 67 |
Trimethylbenzene 1,2,4 | 95-63-6 | 67 |
Trimethylbenzene 1,3,5 | 108-67-8 | 67 |
Vinyl ChlorideC, 6 | 75-01-4 | 0.023 to 2M |
Xylenes (total)6 | 1330-20-7 | 1,400 to 10,000M |
Notes and Abbreviations:
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 The standard for Benzene has been established at the MCL (q.v. 41.17)
3a Standard for Group C compound that has both a published reference dose (non-cancer) and carcinogenic toxicity data and is calculated based on reference dose (non-cancer) toxicity data and then adjusted downward using an uncertainty factor of 10.
3b Standard for Group C compound that has both a published reference dose (non-cancer) and carcinogenic toxicity data and is calculated based on the toxicity data (i.e., non-cancer-based or cancer-based) resulting in the most protective (lowest) water quality standard.
4 The Diisopropylmethylphosphonate (DIMP) standard was adopted in 1993 (q.v. 41.16)
5 PCBs are a class of chemicals that 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 human-health criteria apply to total PCBs, i.e. the sum of all congener or all isomer analyses.
6 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 has been determined to be an acceptable level of this chemical in public water supplies, taking treatability and laboratory detection limits into account. The Commission intends that control requirements for this chemical be implemented to attain a level of ambient water quality that is at least equal to the first number in the range except as follows:
* Wherever the Commission has adopted alternative, site-specific standards for the chemical, the site-specific standards shall apply instead of these statewide standards.
* The implementing agency has determined that setting the protection level to the second number in the range is consistent with the current and reasonably anticipated future uses of the groundwater, factoring in site-specific information, such as: existing prohibitions on groundwater use; whether the location is within the boundaries of an existing or reasonably anticipated public water supply; the proximity of the site to existing and reasonably anticipated water wells; whether or not the aquifer can produce water at a rate capable of supporting the anticipated use; or it can be demonstrated that access to groundwater is prohibited, unavailable or present at insufficient quantities for reliable use.
The Commission does not intend the adoption of this range of standards to result in changes to clean-up requirements previously established by an implementing agency, unless such change is mandated by the implementing agency pursuant to its independent statutory authority.
7 For aquifer storage and recovery facilities, if the source of this chemical in groundwater is potable water provided by a drinking water system with a Colorado PWSID that meets all applicable federal Safe Drinking Water Act and corresponding State requirements at the time that it is utilized for aquifer storage and recovery or artificial recharge, then the separate total trihalomethane standard will apply to the groundwater in question, rather than the individual standards for bromodichloromethane, bromoform, chloroform, and/or dibromochloromethane. For any parameter for which there is a Maximum Containment Level (MCL) established by the Safe Drinking Water Act, as identified in Table A with Footnote "M", the MCL shall apply as the standard for groundwater when potable water is used for ASR or artificial recharge.
8 Mutagenic compound, age dependent factors were used in calculating standard. N/A - not applicable
C Carcinogens classified by the EPA as A, B1, or B2.
M Drinking water MCL.
CAS No. - Chemical Abstracts Service Registry Number THM - Halomethanes
5 CCR 1002-41.5