Code of Colorado Regulations
1000 - Department of Public Health and Environment
1002 - Water Quality Control Commission (1002 Series)
5 CCR 1002-38 - REGULATION NO. 38 - CLASSIFICATIONS AND NUMERIC STANDARDS SOUTH PLATTE RIVER BASIN LARAMIE RIVER BASIN REPUBLICAN RIVER BASIN SMOKY HILL RIVER BASIN
Section 5 CCR 1002-38.20 - STATEMENT OF BASIS AND PURPOSE COAL CREEK, SEGMENT 7(b)

1. This action is consistent with the action taken by the Commission and EPA in adopting and approving use classifications and water quality standards for Ralston Creek and Big Dry Creek which Segment 7(b) of Coal Creek most closely resembles.

2. The Commission has considered only water quality standards for Coal Creek, Segment 7(b) in these proceedings. A regional water quality management plan, including wasteload allocations, for the entire area, taking into account Segments 9 and 10 of Boulder Creek as well as Coal Creek, must be completed before water quality standards requiring advanced wastewater treatment by municipal dischargers can be justified, if at all. The completion of the Lafayette plant expansion will improve the quality of water in the segment and provide a window of opportunity for such information to be produced prior to the imposition of such stringent requirements.

3. A marginal population of non game fish species and other aquatic life exists in Coal Creek. The most significant factors limiting aquatic life in this segment are physical habitat and natural conditions. Due to agricultural diversions and return flows, the stream is extremely shallow and the bed is sandy, not cobble. There are no deep pools or resting places for fish. The stream bank is eroded and lack of riparian vegetation raises both the temperature and pH, which increases the unionized portion of ammonia. Improvements in the physical habitat of both Coal Creek and Boulder Creek might eliminate the need for ammonia removal by the treatment plants, by impeding the conversion of ammonia to its unionized form. However, there is no evidence to support any projection of habitat improvements, and this cannot be required by law.

4. In its natural condition, without the contributions of effluent from Erie, Lafayette, and Louisville, lower Coal Creek was dry a significant portion of the year. Data from the only USGS gauging station on Coal Creek, the Plainview station about 3 miles above Segment 7(b), indicates no flow approximately 21 days in a normal year. Its Q7 10 is zero.

5. Because the segment has a low fish carrying capacity, requiring the three municipal dischargers on the segment to go to some form of AWT would result in only a marginal improvement in the numbers of fish in lower Coal Creek and would result in no greater diversity of species.

6. These changes in water quality standards do not represent a degradation of water quality since existing treatment levels must be maintained to meet technology based requirements. The standards amended by these rules exceed the water quality necessary to protect the existing and designated uses, and are not sufficient to cause a better use to be achieved. Nor will downstream water quality be adversely affected by these amendments. It was previously assumed by the Commission, based on inadequate information, that the standards adopted at that time could be met at existing levels of treatment.

7. Species consistent with existing and designated uses will be protected even though they are not prevalent in numbers or importance. Maintenance of existing quality will not result in increased mortality, reductions in growth, or reproductive impairment.

8. Water quality standards originally established and amended by these rules might necessitate, and result in, an improvement in water quality notwithstanding the fact that such improvement would not enhance the maintenance or attainment of existing and designated uses due to physical habitat and natural conditions.

9. The benefits achieved by the implementation of AWT that would be required to achieve the .1 mg/1 unionized ammonia water quality standard bare an unreasonable relationship to the economic costs and impacts of AWT. This conclusion is based on a consideration of costs for capital improvements and maintenance, and the impact of tap fees and sewer charges as compared to the benefits that might be achieved.

10. "Full protection" of existing species as defined in "EPA Questions and Answers on Anti degradation", United States Environmental Protection Agency, August, 1985, is unwarranted because:

11. Construction of an expanded wastewater treatment plant at Lafayette, as planned, should improve water quality in Coal Creek beyond existing quality, because excess capacity will allow additional nitrification to take place before discharge to the stream.

12. Based on the costs for ammonia removal, the combined cities may well decide that the more cost effective alternative would be to limit discharges to Coal Creek and pump their effluent into lower Boulder Creek. The effect would be to substantially reduce flows in Coal Creek, placing more stress on the fish than under existing conditions, which would have a significant detrimental impact on aquatic life in Coal Creek.

13. Despite the deletion of numeric water quality standards the stream will not experience any water quality degradation and existing aquatic life will be protected. Discharges must meet secondary treatment requirements and may later be required to install AWT to meet water quality standards or wasteload allocations necessary to protect Boulder Creek. The few fish that now live in lower Coal Creek will be protected at current levels, and aquatic life will be enhanced by the achievement of secondary treatment requirements on a more consistent basis. Lafayette can now move ahead with its site applications for an expanded secondary treatment plant, recognizing that it may well have to go to AWT to protect the .06 mg/l unionized ammonia standard in Boulder Creek.

14. More information is necessary to understand the interrelationships between Segment 7(b) of Coal Creek and Segments 9 and 10 of Boulder Creek. The DRCOG, as 208 water quality management agency, has been requested to develop a plan for this sub region, including the development of wasteload allocations necessary to assure compliance with water quality standards and use classifications.

15. The Commission rejects arguments that it should delete all standards for inorganics and metals in this segment, as was done for Big Dry Creek and Lower Ralston Creek. The aquatic life in Lower Coal Creek, however limited in numbers and species, needs to be protected by these standards.

16. This action does not violate the EPA anti degradation policy (40 CFR 131.12) because existing instream uses and the water quality level necessary to protect them shall be continued to be maintained. Furthermore, this action does not constitute allowing lower water quality since the previous .1 mg/l unionized ammonia standard incorporated, and was conditioned by, "footnote" concept and was approved on that basis.

FISCAL IMPACT STATEMENT FOR COAL CREEKSEGMENT 7(b) OF BOULDER CREEK

The deletion of the unionized ammonia standard for Coal Creek will have no identifiable fiscal or economic impact.

The standard for Boulder Creek (into which Coal Creek flows) may ultimately have an economic impact (in the form of increased ammonia removal) upon the three Coal Creek dischargers, since the Boulder Creek standard must nonetheless be protected. This possible result was acknowledged by the Coal Creek discharges but is still speculation at this time.