Near-term | Vulnerability | Resilience | < Selections
Priorities > Resilience
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An indication of habitat resilience may be the watershed features of drainage area, maximum elevation, stream length, and flow.
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Drainage area and maximum elevation directly relate to the amount of water collected.
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Stream length figures in the number of trout populations that may be supported.
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The relationship among streams in area, elevation, and length stays constant even as precipitation declines due to climate change, and that reasonably extends to flows.
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Using the features cited, the 2 tables show 16 streams sorted by expected relative resilience, including 13 from the near-term priority list, plus 3 that have been part of the discussion.
Streams sorted by expected relative resilience
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The tool for sorting the expected relative resilience of all 42 trout-bearing streams in the upper Dolores study area, involving the 5 features shown above and seven other watershed characteristics, can be viewed.
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The spreadsheet tool uses proportional scoring that is based on a largest value. That is, lesser values for each feature are calculated and scored as a percentage of the largest. Scores are summed for a total, enabling the transparent, combined consideration of multiple watershed characteristics to generate the stream scores.
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Using the spreadsheet tool, mean annual July-August flows, which are key for maintaining warm-weather, cold-water habitat, were found to correlate directly and best with the 2 features of drainage areas and highest maximum elevations, making straight-forward the assessment of relative resilience among streams.
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The report "Sustainability of Trout Populations and Role of Tributaries, Examining Water-Temperature Habitat Conditions in the Dolores River Basin," 2020, shows sorting that uses combinations of 12 watershed characteristics, and can be downloaded.
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For further consideration, the table does not include the entire West Fork in the sort. West Fork (38 mi long) differs from the others, downstream of Burro Bridge, by flowing through areas of private ownership of adjacent property, having numerous authorized private water diversions, and having the warmer CS-2 water temperature standards apply below where Fish joins it.
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At West Fork above Burro Bridge (8 mi long), on the other hand, there is neither private property ownership nor authorized water diversion, and the colder CS-1 standards pertain.
Near-term | Vulnerability | Resilience | < Selections
