Favorable streams
A. Overview
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Which streams are most favorable for applying resources to protect and preserve trout populations?
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That is, where would success be most likely and consequential?
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Study results indicate that tributaries above 7500 ft have continuously cold-enough water for trout habitat.
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That would be 41 of the basin’s 42 perennial, trout-bearing tributaries.
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There clearly is no shortage of streams to consider for actions to protect and preserve.
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Temporary dewatering at tributaries is normal, seasonally.
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For instance, it occurs from evaporation during warm-weather months.
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And from reduced runoff and subsurface-water recharge when precipitation is infrequent or low.
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Dewatering, however, can leave small tributaries, or large sections of them, temporarily dry.
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This can result in locations and durations of lost habitat, particularly during drought conditions.
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The 2 tables identify 10 streams that may be more favorable habitat than others, long term, as described below.
Cold-enough | Refuge-reserve | Favorable | Ideas
1. Ten streams with the largest July-August mean flow
2. Ten streams with the largest flows, drainage area, maximum elevation
B. Prioritizing
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What tributaries are most resilient to dewatering?
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Which have the most water to lose before habitat is lost? That is, which streams have the largest flows?
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And what watershed characteristics appear to “explain” large flow?
C. Results
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The 10 streams with the largest July-August mean flow of the 42 studied are identified in table 1 above.
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Results in detail for all 42 streams sorted by July-August mean flow are shown here.
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The stream characteristics data were obtained from application of StreamStats.
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It is an online water resources program developed and hosted by the U.S. Geological Survey.
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The streams with the largest flows also have the largest drainage areas and highest maximum elevations.
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This observation is based on a correlation assessment, with results shown above in table 2.
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This can be interpreted to "explain" large flows, that is, large drainage areas and high maximum elevations.
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The sorting all the streams by drainage area and maximum elevation are shown here.
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As seen above in table 2, 14 sorts in total were made of 8 characteristics.
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The 2nd best correlation resulted from including stream length with drainage area and maximum elevation.
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That result is seen above in table 2 and in detail here.
D. Also for consideration
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At Stoner and Fish, two of the largest-flow streams, water is diverted for agriculture.
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The result reduces stream flow during warm-weather months.
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This may leave stream water temperatures susceptible to increase from ambient warm air.
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It potentially diminishes suitability as trout habitat.
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Runoff from pasture for farm animals can increase sediment and nutrient load to streams.
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It can result in elevated amounts of fecal and total coliform bacteria in the stream water.
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Stoner and 8 other streams had elevated total coliform in July 2020 water samples.
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Stoner also had elevated nitrate concentrations.
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Stoner in July 2020 samples and Coal in September samples had elevated E. coli bacteria concentrations.
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Coliform and E. coli bacteria presence does not mean that water contact results in disease to humans.
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It indicates, instead, that pathogen contamination in the water is possible.
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That is, disease-causing organisms also may be present since coliform and E. coli bacteria were detected.
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Algae growth in the streambed can result from excessive nutrients in the water.
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Such growth is apparent at Stoner in slides 5 and 15 at Streambed conditions in Gallery.
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Nitrogen and phosphorus concentrations were not elevated, however, in September 2020 water samples.
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See Non-metals results, including for nitrogen and phosphorus, (and Metals results) for September 2020.
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It potentially indicates that nutrients do not remain in the water column after entering.
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That is, they likely make their way down the stream and out until the next period of snowmelt or rainfall.
Source
Cold-enough | Refuge-reserve | Favorable | Ideas
