Interpretation: Water quality
A. Summary
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Samples from 9 streams are being analyzed for 12 parameters that Colorado applies for Outstanding Waters status.
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As required for that evaluation, water is collected during each of the 4 seasons.
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The data accumulated are shown at Metals and Non-metals results.
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Of the 5 non-metals parameters, only the E. coli standard has been exceeded.
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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.
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Of the 7 metals parameters for Outstanding Waters qualification, no metals standards were exceeded.
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The closest approach was copper at Coal in winter 2021, 6.7 ug/l as compared with the 14 ug/l standard.
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Zinc at 5.7 ug/l was measured at Coal in the winter 2021 sampling; the hardness-adjusted standard is 189 ug/l.
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Zinc at 2.1 and 2.2 ug/l ostensibly were found at Bear, Coal, and West Fork, Burro Bridge in winter 2021.
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But 2.2 ug/l also was measured in the blank, indicating possibly no zinc was detected at those 3 streams.
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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.
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It is notable that the duplicate sampling and analysis at Bear gave identical results or very nearly so.
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Manganese, 1-6 ug/l, was in all the streams except East Fork, but below the standards, 1600-2100 ug/l.
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No cadmium, lead, silver, or selenium were found at any of the streams in the summer, fall, and winter sampling.
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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.
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The Metals results, which importantly pertain to potential toxicity, are consistent with Reasonable expectations.
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While not an Outstanding Waters parameter, total coliform also was measured for more indication of water quality.
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The standard of 200/100 ml for CO Recreation Class I water was exceeded in summer 2020 at 10 of the 12 streams.
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Only Barlow, East Fork, and Slate were below the CO total coliform standard in the summer 2020 sampling.
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Total coliform presence likely results from fecal material carried by runoff into the streams, that is, from grazing.
B. Winter 2021
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No non-metals concentrations exceeded CO water quality standards applied for Outstanding Waters consideration.
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As well, total coliform was below the standard for CO Recreations Class I water (Rule 34). See Non-metals results.
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No dissolved cadmium, lead, or silver were detected at the 9 sampling sites. See Metals results and Detection limits.
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Copper, manganese, zinc, and selenium were detected, but at concentrations below hardness-adjusted standards.
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Results from analysis of the Bear and Bear duplicate samples were identical or very similar.
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The blank sample showed a small concentration of zinc.
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It was the same amount of zinc measured in the Bear and East Fork samples, and roughly half that at Coal.
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The blank showed a small copper concentration that was the same at Bear, Slate, and Wildcat.
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Coal had an order of magnitude more copper, but still less than half the standard.
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Manganese was the metal detected at the greatest number of sites, as was the case in summer and fall sampling.
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All streams were sampled on 1/18/2021, except West Fork, Burro Bridge, which was sampled on 2/8/2021.
C. Fall 2020
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E. coli at Coal was 127/100 ml, which exceeded the CO standard of 126/100 ml (Rule 34). See Non-metals results.
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Total coliform was 1733/100 ml at Coal and 1120/100 ml at Stoner, Lower, which exceeded 200/100 ml (Rule 34).
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Nitrate was detected at 3 of the 10 streams, none higher than the nitrate standard of 10 mg/l (Rule 34).
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Ammonia was not detected at any of the sampling sites.
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pH at the streams was within the CO standard of 6.5-9.0 (Rule 34) .
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Dissolved oxygen concentrations at each of the streams met the CO standard, including for spawning (Rule 34).
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Manganese was detected in 7 of the 10 samples, with concentrations below the hardness-adjusted standard (Rule 31).
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Selenium was detected only at East Fork and Slate, at concentrations below the hardness-adjusted standard (Rule 31).
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Cadmium, copper, lead, silver, and zinc were not detected at any of the sampling locations. See Metals results.
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Phosphorus and nitrogen were analyzed at three stream locations. See Nutrients results.
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Nitrate was detected, 0.06 mg/l at East Fork, below the interim nutrient standard for total nitrogen, 1.25 mg/l (Rule 31).
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All streams were sampled on 9/21/2020, except Stoner Upper and West Fork, Burro Bridged, sampled 9/23/2020.
D. Summer 2020
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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.
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E. coli was not detected above the standard at the other 8 sites.
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Total coliform was 210-1120 per 100 ml at nine of the 12 streams, exceeding the standard of 200 per 100 ml (Rule 34).
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Nitrite was 0.12 mg/l at Stoner, which exceeded the nitrite standard of 0.05 mg/l (Rule 34) .
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It was detected in concentrations below the standard at Barlow, East Fork, and Wildcat.
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Nitrate was detected in 6 of the 12 streams. No concentrations exceeded the nitrate standard of 10 mg/l (Rule 34).
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Those streams were the 4 in which nitrite was detected, along with Slate and West Fork at Burro Bridge .
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Ammonia was not detected in any of the 12 streams.
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pH at the 12 streams was within the CO standard of 6.5-9.0 (Rule 34) .
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Dissolved oxygen concentrations at the 12 sampling sites met the CO standard, including for spawning (Rule 34).
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Manganese was detected in 7 of the 12 streams; all values were below the hardness-adjusted standard (Rule 31).
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Zinc was detected at 2 streams; concentrations were below the hardness-adjusted standard (Rule 31).
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Cadmium, copper, lead, silver, and selenium were not detected in any of the 12 streams. See Metals results.
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Arsenic and copper were analyzed in water from Roaring Forks, and none was detected.
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The stream is on Colorado's list to monitor and evaluate (M&E) for possible metals contamination (Rule 93).
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Eight of the 12 streams were sampled on 7/14/2020 and the remaining four on 7/16/2020.
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