​Favorable streams

A. Overview

  1. Which streams are most favorable for applying resources to protect and preserve trout populations?

  2. That is, where would success be most likely and consequential?

  3. Study results indicate that tributaries above 7500 ft have continuously cold-enough water for trout habitat.

  4. That would be 41 of the basin’s 42 perennial, trout-bearing tributaries.

  5. There clearly is no shortage of streams to consider for actions to protect and preserve.

  6. Temporary dewatering at tributaries is normal, seasonally.

  7. For instance, it occurs from evaporation during warm-weather months.

  8. And from reduced runoff and subsurface-water recharge when precipitation is infrequent or low.

  9. Dewatering, however, can leave small tributaries, or large sections of them, temporarily dry.

  10. This can result in locations and durations of lost habitat, particularly during drought conditions.

  11. The 2 tables identify 10 streams that may be more favorable habitat than others, long term, as described below.

  Cold-enough | Refuge-reserve | Favorable

1. Ten streams with the largest July-August mean flow
Ranked by July-August mean flow
2. Ten streams with the largest flows, drainage area, maximum elevation

B. Prioritizing​

  1. What tributaries are most resilient to dewatering?

  2. Which have the most water to lose before habitat is lost? That is, which streams have the largest flows?

  3. And what watershed characteristics appear to “explain” large flow?

C. Results

  1. The 10 streams with the largest July-August mean flow of the 42 studied are identified in table 1 above.

  2. Results in detail for all 42 streams sorted by July-August mean flow are shown here.

  3. The stream characteristics data were obtained from application of StreamStats.

  4. It is an online water resources program developed and hosted by the U.S. Geological Survey.

  5. The streams with the largest flows also have the largest drainage areas and highest maximum elevations.

  6. This observation is based on a correlation assessment, with results shown above in table 2.

  7. This can be interpreted to "explain" large flows, that is, large drainage areas and high maximum elevations.

  8. The sorting all the streams by drainage area and maximum elevation are shown here.

  9. As seen above in table 2, 14 sorts in total were made of 8 characteristics.

  10. The 2nd best correlation resulted from including stream length with drainage area and maximum elevation.

  11. That result is seen above in table 2 and in detail here.​ 

D. Also for consideration​

  1. At Stoner and Fish, two of the largest-flow streams, water is diverted for agriculture.

  2. The result reduces stream flow during warm-weather months.

  3. This may leave stream water temperatures susceptible to increase from ambient warm air.

  4. It potentially diminishes suitability as trout habitat.

  5. Runoff from pasture for farm animals can increase sediment and nutrient load to streams.

  6. It can result in elevated amounts of fecal and total coliform bacteria in the stream water.

  7. Stoner and 8 other streams had elevated total coliform in July 2020 water samples.

  8. Stoner also had elevated nitrate concentrations.

  9. Stoner in July 2020 samples and Coal in September samples had elevated E. coli bacteria concentrations.

  10. Coliform and E. coli bacteria presence does not mean that water contact results in disease to humans.

  11. It indicates, instead, that pathogen contamination in the water is possible.

  12. That is, disease-causing organisms also may be present since coliform and E. coli bacteria were detected.

  13. Algae growth in the streambed can result from excessive nutrients in the water.

  14. Such growth is apparent at Stoner in slides 5 and 15 at Streambed conditions in Gallery.

  15. Nitrogen and phosphorus concentrations were not elevated, however, in September 2020 water samples.

  16. See Non-metals results, including for nitrogen and phosphorus, (and Metals results) for September 2020.

  17. It potentially indicates that nutrients do not remain in the water column after entering.

  18. That is, they likely make their way down the stream and out until the next period of snowmelt or rainfall.



  Cold-enough | Refuge-reserve | Favorable