5 Colo. Code Regs. § 1002-32.6
The numeric standards for various parameters in this regulation and in the tables in Appendix 32 1 were assigned by the Commission after a careful analysis of the data presented on actual stream conditions and on actual and potential water uses. For each parameter listed in the tables in Appendix 32-1, only the most stringent standard is shown. Additional, less stringent standards may apply to protect additional uses and can be found in the tables in Regulation No. 31.
Numeric standards are not assigned for all parameters listed in the tables in Regulation No. 31. If additional numeric standards are found to be needed during future periodic reviews, they can be assigned by following the proper hearing procedures.
Ac | = | acute (1-day) |
AEL | = | alternative effluent limit |
°C | = | degrees Celsius |
Ch | = | chronic (30-day) |
CL | = | cold lake temperature tier |
CLL | = | cold large lake temperature tier |
CS-I | = | cold stream temperature tier one |
CS-II | = | cold stream temperature tier two |
D.O. | = | dissolved oxygen |
DM | = | daily maximum temperature |
DUWS | = | direct use water supply |
E. coli | = | Escherichia coli |
mg/L | = | milligrams per liter |
MWAT | = | maximum weekly average temperature |
OW | = | outstanding waters |
sp | = | spawning |
SSE | = | site-specific equation |
T | = | total recoverable |
t | = | total |
tr | = | trout |
TVS | = | table value standard |
µg/L | = | micrograms per liter |
UP | = | use-protected |
WS | = | water supply |
WS-I | = | warm stream temperature tier one |
WS-II | = | warm stream temperature tier two |
WS-III | = | warm stream temperature tier three |
WL | = | warm lake temperature tier |
Iron (chronic) | = | WS |
Manganese (chronic) | = | WS |
Sulfate (chronic) | = | WS |
These abbreviations mean: For all surface waters with an actual water supply use, the less restrictive of the following two options shall apply as numerical standards, as specified in the Basic Standards and Methodologies at 31.16 Table II and III:
Iron = | 300 µg/L (dissolved) |
Manganese = | 50 µg/L (dissolved) |
Sulfate = | 250 mg/L (dissolved) |
For all surface waters with a "water supply" classification that are not in actual use as a water supply, no water supply standards are applied for iron, manganese or sulfate, unless the Commission determines as the result of a site-specific rulemaking hearing that such standards are appropriate.
In certain instances in the tables in Appendix 32-1, the designation "TVS" is used to indicate that for a particular parameter a "table value standard" has been adopted. This designation refers to numerical criteria set forth in the Basic Standards and Methodologies for Surface Water. The criteria for which the TVS are applicable are on the following table.
TABLE VALUE STANDARDS
(Concentrations in µg/L unless noted)
TABLE VALUE STANDARDS - FOOTNOTES
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The following criteria shall be used when assessing whether a specified waterbody is in attainment of the specified standard.
* Upper Reach: From Pueblo Dam to the Pueblo Hatchery outfall (38.266697, -104.711983).
* Mid Reach: From the Pueblo Hatchery outfall (38.266697, -104.711983) to the end of the Pueblo Hatchery mixing zone (38.264213, -104.708524).
* Lower Reach: From the end of the Pueblo Hatchery mixing zone (38.264213, -104.708524) to the confluence with Wildhorse/Dry Creek Arroyo.
Month | Reach | MWAT °C | DM °C |
Jan-June | All | CS-II | CS-II |
July | Upper | CS-II | CS-II |
Mid | CS-II | CS-II | |
Lower | 18.5 | CS-II | |
Aug | Upper | 18.9 | CS-II |
Mid | 19.1 | CS-II | |
Lower | 20.0 | 26.0 | |
Sept | Upper | 19.9 | CS-II |
Mid | 20.0 | CS-II | |
Lower | 20.9 | 24.6 | |
Oct | Upper | 19.9 | CS-II |
Mid | 20.0 | CS-II | |
Lower | 19.6 | CS-II | |
Nov | Upper | 15.7 | 15.8 |
Mid | 15.5 | 15.2 | |
Lower | 14.7 | 15.9 | |
Dec | Upper | 10.1 | CS-II |
Mid | 9.9 | CS-II | |
Lower | 9.6 | CS-II |
For assessment, a 1-in-3 year allowable exceedance frequency shall be used to assess these site-specific standards, consistent with 31.16 Table I Footnotes 5a and 5b. Because the site-specific standards are ambient, and not biologically-based, the Warming Event allowance does not apply.
* Wildhorse Creek above Pesthouse Gulch: 38.296478, -104.649201
* Pesthouse above No Name: 38.309568, -104.672244
Determinations of attainment of the chronic and acute selenium standards will be based on the 85th and 95th percentile, respectively of all available data from the segment. The selenium assessment locations are:
* SC-5: St. Charles River approximately one mile downstream of the confluence with Edson Arroyo.
* SC-6-US: St. Charles River upstream of the confluence with Thomkins Arroyo and the Comanche discharge.
* SC-7: Approximately 2 miles upstream of the Bessemer Canal crossing.
* SC-8: Immediately upstream of the Bessemer Canal crossing.
* SC-9: St. Charles River downstream of where the river flows under U.S. Highway 50, approximately 3 miles upstream of the confluence with the Arkansas River.
* Site 7b (USGS Site 381602104435200): Near the dam and the south outlet works
The stream classifications and water quality standards tables in Appendix 32-1 are incorporated herein by reference.
The following is information regarding duration and measured form of standards in Appendix 32-1:
Discharger-specific Variance, City of Pueblo James R. DiIorio Water Reclamation Facility (CO0026646): Adopted 6/12/2018.
Selenium (acute): AEL=narrative;
Selenium (chronic): AEL=narrative;
Sulfate (chronic): AEL=narrative.
Expiration date: 12/31/2028.
Narrative alternative effluent limit: During the DSV term, Pueblo will be required to spend $10 million to implement a comprehensive source control, sampling, analysis, and optimization adaptive management program to reduce selenium and sulfate concentrations in the effluent as much as feasible and to ensure that the discharge does not contribute to any lowering of the currently attained ambient water quality. The adaptive management program will include the following elements, in order of priority:
* Lining up to 175,000 ft2 in the sewer collection system in Basins 2 and 3.
* Sealing up to 400 manholes in Basins 2 and 3.
* The amount of sewer lining and manhole sealing may be reduced by:
* Repair of service taps in poor condition;
* Repair of service lines in poor condition; or
* Additional effort where epoxy sealing of manholes is insufficient to control I & I.
* A comprehensive long-term sampling and analysis program to identify source control projects and evaluate the effectiveness of implemented controls.
* Investigation of the contribution from sump pumps.
* Pilot testing to determine the feasibility of treatment optimization to reduce selenium, and implementation of feasible treatment optimization measures.
Selenium (acute): AEL=no limit;
Selenium (chronic): AEL=0.37 lbs/day as a 12-month rolling average.
Includes a Pollutant Minimization Program. (see 32.71(A))
Expiration date: 12/31/2026.
Selenium (chronic): AEL = narrative.
Includes a Pollutant Minimization Program. (see 32.71(A))
Expiration Date: 12/31/2025.
Narrative alternative effluent limit: During the DSV term, Las Animas will implement a Pollutant Minimization Plan, which is expected to result in effluent concentrations between 0.8 - 28.4 µg/L. The following measures are required during the term of the variance to reduce selenium concentrations as much as feasible and to ensure the discharge does not contribute to any lowering of ambient in-stream water quality:
* Monitor selenium concentrations in each municipal water well and use the wells with the lowest selenium concentrations to meet water demand to the maximum extent feasible
* Initiate a water conservation program
* Locate and repair sources of water loss in the water distribution system
* Maintain the ongoing sanitary sewer collection system replacement program to address groundwater infiltration
5 CCR 1002-32.6