Stoner example

A. Introduction

How do E. coli and total coliform concentrations at Stoner compare with water quality criteria?
Colorado applies a standard of 126/100 ml for E. Coli in evaluating streams for classification as Outstanding Waters [1].
Total coliform is not part of consideration for Outstanding Waters, but a CO recreational stream standard is 200/100 ml [1].
Sampling sites and 2 other locations are briefly characterized in the table below.

As seen below, the highest E. coli and total coliform values were observed at the most-downstream (Lower) location.
The E. coli standard was exceeded only at that site, and that was in July 2020 and 2021.
That location also had E. coli values of only 1.0/100 ml in January 2020 and May 2021.
The total coliform standard was exceeded at all three locations, and by the highest amounts at the most-downstream site.

A beaver dam at least 6 ft high, appearing structurally sound, divides the upper 8 mi from the rest of the 19-mi stream.
That large dam, along with beaver ponds and the 2 sampling sites upstream from it are shown here.
The sampling sites in that upper portion had no exceedances in E. coli concentrations, even in warm weather.
That upper portion drains approximately 13 sq mi.
A best use of that reach may be for protecting cutthroat trout, as part of CO's cutthroat conservation strategy [2-4].
About 6 mi of "suitable steam habitat" may be needed to overcome isolation and "maintain genetic diversity" [5].
Translocation success in 27 Colorado and New Mexico streams increased to 90% as drainage area reached 13 sq mi [6].
Water quality standards were not exceeded for the other 11 parameters used in qualifying streams as Outstanding Waters.
That upper 8-mile reach of Stoner may be suitable both as Outstanding Waters and as isolated cutthroat trout habitat.

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