Stream sorting tool 

  A. Introduction

  1. The tool enables sorting of the perennial, trout-bearing streams based on 12 watershed features.

  2. Those features, or characteristics, are:​

  • Drainage area, sq mi

  • Maximum elevation, ft (x 1,000)

  • Stream length, mi

  • Slope, mean, %

  • Vegetation cover, %

  • Precipitation, in, annual

  • Flow, cfs, July, mean

  • Flow, cfs, August, mean

  • Flow, cfs, July-August, mean

  • Flow, cfs, annual, mean

  • Time of concentration (TOC), hr

  • Outfall elevation, ft​

  B. Approach

  1. The sorting uses proportional scoring.​

  2. That is, the highest value of a characteristic is given a score of 1.00 (or 100).

  3. A lower value is scored as a percentage of that highest value.

  4. For example, Stoner has the highest drainage area, 45.6 sq mi, and is scored 1.00 (or 100) in drainage area.

  5. Bear has a drainage area of 33.7 sq mi and is scored 0.74 (or 74) in drainage area.

  6. The scores for each characteristic are summed in a total for each stream, enabling comparison among the streams.

  7. Highest total scores of favorable characteristics logically would indicate the streams most resilient as trout habitat.

  8. They would be the streams more likely than others to maintain sufficient flow and habitat volume despite climate change.

  9. The information source for the characteristics is the U.S. Geological Survey online water-resources program StreamStats.

Simplified example of proportional scoring of streams

Sort18.jpg

  C. Download

  1. The sorting tool is in the form of an Excel spreadsheet.

  2. Click here to download it.

  3. In example applications of the tool, Dolores streams are sorted by:

  D. Application​

  1. By default, all streams are included in a sort.

  2. To narrow the sort to selected streams, replace 1 with 0 in the column labeled Sort, in/out: 1/0.

  3. To narrow the sort to selected characteristics, replace 1 with 0 in the row labeled Weight.

  4. The maximum value for each characteristic is given in the row labeled Best and will need to pertain to the selection.

  5. That is, when a subset is made, inspect the values to ensure the maximums apply to that subset of streams.

  6. Replace with the correct value when necessary.

  7. For example, if Stoner is excluded in a sorting and Bear remains, the new Best drainage area is 33.7 sq mi, not 45.6 sq mi.

  8. So the value of 45.6 is replaced by 33.7 in Best in the Drainage area column.

  9. For each subset, inspect each column to ensure the applicable maximum value is entered in the row of Best values.

  10. The tool will automatically recalculate individual scores for the characteristics and total scores for the streams.