Sorting for priority
A. Introduction
-
What streams have the largest habitat volume, greatest resilience to dewatering, and most habitat length?
-
Those characteristics could be a basis for good choices in efforts to protect and preserve trout habitat.
-
Results of sorting using combined and individual characteristics are shown and described below.
Protections | Priority | Comparison | Tool
B. Candidate streams
-
Protections underway already at 22 streams include Outstanding Waters and Instream Flow Program protection.
-
Are all 22 streams good candidates for prioritization?
-
Fish and Stoner have active surface water diversions for agriculture.
-
Consequently, their stream flows are reduced during warm weather, increasing habitat stress.
-
That is, they are not good candidates to consider further for habitat preservation resources.
-
Taylor temporarily dewatered to dryness in 2019, so it is not a good candidate, either.
-
Rough canyon is a tributary of Roaring Forks, so there is no reason to consider it separately.
-
This leaves 18 of the 22 streams as candidates for proceeding with an approach to prioritization.
C. Sorting the candidates
a. Background
-
Flow can be used to represent habitat volume.
-
Resilience would be evident from flow amounts during summertime conditions and year around.
-
Flow was found to correlate with stream drainage area and maximum elevation.
-
Logically, larger drainage area would collect more precipitation for generating stream flow.
-
And higher elevations would mean more snowmelt to contribute to the recharge of stream baseflow.
-
See sorting with stream characteristics.
-
Including stream length produced the next best correlation.
-
Stream characteristics for the correlation assessments were from application of StreamStats.
b. Sorting
-
Table 1 above shows the 18 candidate streams sorted by those characteristics identified in table 2.
-
Scores are proportional, based on comparison with the highest value for each characteristic.
-
Individual scores were summed for total scores.
-
That is, for example, Bear has the highest July-August mean flow, 49.55 cfs, and obtains a score of 100.
-
East Fork has a July-August mean flow of 35.70 cfs, which is 72 percent of 49.55 cfs.
-
The sum of proportional scores for Bear is 493, shown in the table, so its overall score is 100.
-
Bear is at the top of the sorting of candidates, based on the characteristics used.
-
East Fork has 68 percent of Bear’s score and is second in the sorting.
-
For comparison, table 2 shows results with the same stream characteristics applied individually.
-
There is both similarity and variation within the table 2 listings.
-
For example, Bear and Roaring Forks are high in 4 of the 5 sorts.
-
Kilpacker is at the bottom, at the top, and roughly in the middle in 4 of the sorts.
Protections | Priority | Comparison | Tool