Water quality

A. Summary

  1. Samples from 9 streams are being analyzed for 12 parameters that Colorado applies for Outstanding Waters status.

  2. As required for that evaluation, water is collected during each of the 4 seasons.

  3. The data accumulated are shown at Metals  and Non-metals results.

  4. Of the 5 non-metals parameters, only the E. coli standard has been exceeded.

  5. It was 517/100 ml at Stoner in summer 2020 and 127/100 ml at Coal in fall 2020, the standard being 126/100 ml.

  6. Of the 7 metals parameters for Outstanding Waters qualification, no metals standards were exceeded.

  7. The closest approach was copper at Coal in winter 2021, 6.7 ug/l as compared with the 14 ug/l standard.

  8. Zinc at 5.7 ug/l was measured at Coal in the winter 2021 sampling; the hardness-adjusted standard is 189 ug/l.

  9. Zinc at 2.1 and 2.2 ug/l ostensibly were found at Bear, Coal, and West Fork, Burro Bridge in winter 2021.

  10. But 2.2 ug/l also was measured in the blank, indicating possibly no zinc was detected at those 3 streams.

  11. That is, zinc could be in the stream samples at 2.1-2.2 ug/l as a artifact of the equipment or the analysis process.

  12. It is notable that the duplicate sampling and analysis at Bear gave identical results or very nearly so.

  13. Manganese, 1-6 ug/l, was in all the streams except East Fork, but below the standards, 1600-2100 ug/l.

  14. No cadmium, lead, silver, or selenium were found at any of the streams in the summer, fall, and winter sampling.

  15. Selenium was an exception at East Fork and Slate, 1.2 and 2.1 ug/l in the winter sampling; standard, 4.6 ug/l.

  16. The Metals results, which importantly pertain to potential toxicity, are consistent with Reasonable expectations.

  17. While not an Outstanding Waters parameter, total coliform also was measured for more indication of water quality.

  18. The standard of 200/100 ml for CO Recreation Class I water was exceeded in summer 2020 at 10 of the 12 streams.

  19. Only Barlow, East Fork, and Slate were below the CO total coliform standard in the summer 2020 sampling.

  20. Total coliform presence likely results from fecal material carried by runoff into the streams, that is, from grazing.

B. Winter 2021

  1. No non-metals concentrations exceeded CO water quality standards applied for Outstanding Waters consideration.

  2. As well, total coliform was below the standard for CO Recreations Class I water (Rule 34). See Non-metals results.

  3. No dissolved cadmium, lead, or silver were detected at the 9 sampling sites. See Metals results and Detection limits.

  4. Copper, manganese, zinc, and selenium were detected, but at concentrations below hardness-adjusted standards.

  5. Results from analysis of the Bear and Bear duplicate samples were identical or very similar.

  6. The blank sample showed a small concentration of zinc.

  7. It was the same amount of zinc measured in the Bear and East Fork samples, and roughly half that at Coal.

  8. The blank showed a small copper concentration that was the same at Bear, Slate, and Wildcat.

  9. Coal had an order of magnitude more copper, but still less than half the standard.

  10. Manganese was the metal detected at the greatest number of sites, as was the case in summer and fall sampling.

  11. All streams were sampled on 1/18/2021, except West Fork, Burro Bridge, which was sampled on 2/8/2021.

C. Fall 2020​

  1. E. coli at Coal was 127/100 ml, which exceeded the CO standard of 126/100 ml (Rule 34). See Non-metals results.

  2. Total coliform was 1733/100 ml at Coal and 1120/100 ml at Stoner, Lower, which exceeded 200/100 ml (Rule 34).

  3. Nitrate was detected at 3 of the 10 streams, none higher than the nitrate standard of 10 mg/l (Rule 34).

  4. Ammonia was not detected at any of the sampling sites.

  5. pH at the streams was within the CO standard of 6.5-9.0 (Rule 34) .

  6. Dissolved oxygen concentrations at each of the streams met the CO standard, including for spawning (Rule 34).

  7. Manganese was detected in 7 of the 10 samples, with concentrations below the hardness-adjusted standard (Rule 31).

  8. Selenium was detected only at East Fork and Slate, at concentrations below the hardness-adjusted standard (Rule 31).

  9. Cadmium, copper, lead, silver, and zinc were not detected at any of the sampling locations. See Metals results.

  10. Phosphorus and nitrogen were analyzed at three stream locations. See Nutrients results.

  11. Nitrate was detected, 0.06 mg/l at East Fork, below the interim nutrient standard for total nitrogen, 1.25 mg/l (Rule 31).

  12. All streams were sampled on 9/21/2020, except Stoner Upper and West Fork, Burro Bridged, sampled 9/23/2020.

D. Summer 2020

  1. E. coli at Stoner was 517 per 100 ml, higher than the CO standard of  126 per 100 ml (Rule 31). See Non-metals results.

  2. E. coli was not detected above the standard at the other 8 sites.

  3. Total coliform was 210-1120 per 100 ml at nine of the 12 streams, exceeding the standard of 200 per 100 ml (Rule 34). 

  4. Nitrite was 0.12 mg/l at Stoner, which exceeded the nitrite standard of 0.05 mg/l (Rule 34) .

  5. It was detected in concentrations below the standard at Barlow, East Fork, and Wildcat.

  6. Nitrate was detected in 6 of the 12 streams. No concentrations exceeded the nitrate standard of 10 mg/l (Rule 34).

  7. Those streams were the 4 in which nitrite was detected, along with Slate and West Fork at Burro Bridge .

  8. Ammonia was not detected in any of the 12 streams.

  9. pH at the 12 streams was within the CO standard of 6.5-9.0 (Rule 34) .

  10. Dissolved oxygen concentrations at the 12 sampling sites met the CO standard, including for spawning (Rule 34).

  11. Manganese was detected in 7 of the 12 streams; all values were below the hardness-adjusted standard (Rule 31).

  12. Zinc was detected at 2  streams; concentrations were below the hardness-adjusted standard (Rule 31).

  13. Cadmium, copper, lead, silver, and selenium were not detected in any of the 12 streams. See Metals results.

  14. Arsenic and copper were analyzed in water from Roaring Forks, and none was detected.

  15. The stream is on Colorado's list to monitor and evaluate (M&E) for possible metals contamination (Rule 93).

  16. Eight of the 12 streams were sampled on 7/14/2020 and the remaining four on 7/16/2020.

References

  1. Code of Colorado Regulations, Water Quality Control Commission, 5 CCR 1002-34, Regulation No. 34, "Classifications and Numeric Standards for the San Juan River and Dolores River Basins" (Rule 34).

  2. Code of Colorado Regulations, Water Quality Control Commission, 5 CCR 1002-31, Regulation No. 31, "The Basic Standards and Methodologies for Surface Water" (Rule 31).

Findings: Water quality | Water temperature 

Findings: Water quality | Water temperature