Looking forward

What currently is in place for protection, what additionally is underway, and, for going forward, what is a reasoned approach for further planning to protect and preserve trout habitat in the basin?

I. Briefly

  1. For the purpose of protecting and preserving trout habitat, where can actions be directed to be most effective--and efficient, given the normal reality of limited resources?

  2. An approach can be based on the streams in a basin that have the most habitat, the greatest resilience against dewatering, and the most stable, cold-enough temperatures, that is, where proceeding with actions can be most favorably consequential.

  3. An additional objective can be minimization of opportunities for contention with existing land and water use.

  4. The result in pursuing this approach for the study area, as described below in detail, is identification of 8 out of the 42 perennial, trout-bearing streams at which actions taken can reasonably be expected to meet the purpose well, to be successful in plans to further protect and preserve habitat, the largest amount of habitat for the efforts and costs invested, which is to say, the opportunity to be the most effective and efficient.

II. In detail

A. Current conditions

  1. Shown in the table below, 8 streams, or reaches within them, have been designated by Colorado as Outstanding Waters (see Outstanding waters).

  2. Also, 17 streams, not including the West Fork, into which some of the identified tributaries drain, are part of Colorado's Instream Flow Program (see Instream flow).

  3. That is a total of 21 individual streams, with 4 that are both Outstanding Waters and enrolled in Instream Flow.

  4. Six additional streams are candidates to be proposed for Outstanding Waters designation, along with reaches in 3 streams in which portions already have that status (again, see Outstanding waters).

  5. Five of the 6 candidates are in the Instream Flow Program.

  6. The total is 22 individual streams that already are classified as Outstanding Waters or are potential candidates, and already are part of the Instream Flow Program, as listed in the table below.

  7. Of those 22 streams, 18 are known to have cutthroat trout populations, identified in the table below.

  8. Nine of those 22 streams have no water diversion structures, and 2 have only one diversion (again, Instream flow).

  9. Seven of those 22 streams drain inactive range allotments, that is, have no cattle or sheep grazing in the watershed; and 8 of them drain active range allotments (see Range allotments).

B. Stream and watershed characteristics

  1. Streams with larger flows have greater habitat volume and, thereby, more water to lose, that is, from dewatering, before trout habitat is lost, as described in Favorable streams at Interpretations.

  2. Those with the larger drainage areas and higher maximum elevations likely are more resilient to dewatering, also as suggested at Favorable streams.

  3. The streams with larger drainage areas and higher maximum elevations tend to have greater stream lengths.

  4. The typically shaded portions at middle and lower elevations in those streams can cool and moderate the temperature fluctuations in water arriving from higher-elevation exposure to direct solar radiation.

  5. There is exposure and greater temperature variation at higher elevations at Coal and Slate. (See "B. Comparisons with criteria" at Water temperature in Findings. Also, see slides 3-5 at Watershed features in Gallery.)

  6. Temperature variation during July-Augusts at the highest Coal and Slate measurement sites, 10,064 and 10,036 ft, was 31 and 32 F, as compared with 21 F at Priest, 10,599 ft, where streamflow is shaded at that elevation and above. (See Data summary at Data and slide 5 at Watershed features.) Logically, greater is more stressful to trout than lesser variation.

  7. Temperatures measured during July-August at the highest Coal measurement site showed fluctuation up to the CO acute criterion, 71.1F. (See WAT-TAT summary.)

  8. Temperature variation decreased with measurement elevations at those streams. (See the "Variation" column in Data summary.)

  9. The results with greater stream length are extended, downstream portions of stable (reduced variation), cold-enough temperatures for trout habitat.

  10. The table below shows the 22 streams ranked by habitat volume (larger July-August and annual mean flows), resilience (larger drainage areas and higher maximum elevations), and stable, cold-enough water temperatures (greater stream length, along with larger drainage areas and higher maximum elevations).

  11. See July-August flow, annual flow, drainage area and maximum elevation, and stream length for those rankings. The data were compiled from application of the U.S. Geological Survey water resources program StreamStats, as cited in Favorable streams.

  12. The ranking totals for each stream are shown in the table below and the streams are listed in the order of those totals, from lowest to highest, the lower values being more favorable.

C. Factors​ and options

  1. Fish, which ranks 2nd in the table, has multiple water diversions (see Instream flow) and drains active range allotments.

  2. That applies also to Stoner, which is 3rd in the table's ranking.

  3. It makes them less attractive candidates than some other streams for the expenditure of resources intended to improve trout habitat protection and preservation.

  4. Despite being 11th in the ranking, in the middle out of 22, Taylor dewatered to a dry streambed in fall 2020, so it is not an attractive candidate either (see slide 10 in Drought flows at Gallery).

  5. These 5 streams, Bear, East Fork, Scotch, Barlow, and Snow Spur, are ranked high in the table below, and in that order.

  6. Four of them have no surface water diversions and the other, only one (see Instream flow), and they drain no active range allotments.

  7. In addition, Barlow has a lake and flood plain and Scotch has beaver ponds and flood plain that contribute to recharge of downstream baseflow. (See slides 1 and 2 at Watershed features in Gallery.)

  8. Also ranked high, but with active range allotments, are 3 more streams, Coal, Roaring Forks, Slate.

  9. This brings the total to 8 streams that could be attractive subjects for resources intended to further the protection and preservation of trout habitat for both native and wild species.

  10. As seen in the table, 7 of those 8 have known populations of the native trout species, cutthroat; Scotch currently is the exception.

D. Going forward​

a. Reasoning

  1. Resources for actions to protect and preserve trout habitat understandably are limited. Where might they be applied for the greatest effectiveness and efficiency--for the most success?

  2. The 10 tributaries having the largest flows account for 60 percent of the total flow at trout-bearing streams in the study area.

  3. As an approach for having greatest effectiveness and efficiency, it seems reasonable to consider directing resources for habitat protection and preservation at those largest-flow tributaries.

  4. They can accommodate the largest trout populations, and they have the most water to lose before habitat is lost.

  5. They have the largest drainage area for collecting precipitation and producing stream flow.

  6. They have the highest maximum elevations, where snow may accumulate, the melting of which recharges subsurface water for stream baseflow and adds to springtime and early summer surface water flow.

  7. They have the greatest length of shaded, cooler water, which can stabilize the fluctuating, warm temperatures in waters arriving from above tree lines, minimizing habitat stress from temperature variation.

  8. In summary, the largest-flow tributaries have the most habitat volume, the anticipated highest resilience to dewatering, and the most stable, cold-enough water temperatures in the tributary network.

b. Highest priority

  1. Those streams in the study area having the most habitat volume, based on annual and July-August mean flows, are ranked in the table below, with numbers for the top 10 in red.

  2. High resilience refers to large drainage areas and high maximum elevations, and streams with those characteristics also are ranked in the table; high annual and July-August mean flows were found to correlate with those characteristics.

  3. In anecdotal support, photographs taken during October 2020 drought flows show higher water volumes/flows at streams with larger drainage areas and higher maximum elevations.

  4. Stable (and cold-enough) temperatures follow from greater stream lengths, as described above in items 3-9 in "B. Stream and watershed characteristics."

  5. So, shown in the table, streams also are ranked by greatest length, in combination with largest drainage area and highest maximum elevations. (See the sort by drainage area, maximum elevation, and length.)

  6. As determined in this study, continuously cold-enough water is (1) at upper elevations in the main stem, those elevations depending on a particular summer season’s warm-weather conditions, for example, at 8550 ft and above in summer 2018, which was during drought.

  7. And (2) at tributaries with outfalls above 7500 ft, irrespective of particular summer conditions, including drought.

  8. These findings about warm-weather habitat health result from comparing measured temperatures, after converting them to weekly average temperatures (WAT) and two-hour average temperatures (TAT) values, with the Colorado cold stream 1 (CS-1) chronic and acute water temperature criteria that are relevant for this study area and the summer period.

c. Flow and water quality protection

  1. All the highest priority streams already have Instream Flow Program participation, which gives some protection to minimum flows.

  2. The upper reaches of two of the highest priority streams have Outstanding Waters designation, protecting water quality.

  3. Three more of the highest priority streams, along with the lower portions of 2 of the highest priority streams that already have the classification, are current candidates for proposal to Colorado for designation as Outstanding Waters.

  4. It seems reasonable and forward-thinking to include all the highest priority streams in efforts to obtain Outstanding Waters status, that is, to add Barlow, Roaring Forks, and Scotch to the candidates list; or plan that they are part of the next proposal cycle.

d. Cutthroat trout factor​

  1. An important factor in Colorado's evaluation for Outstanding Waters status is protection of threatened species, which applies to cutthroat trout.

  2. Shown in the table below, 7 of the 8 highest priority streams host cutthroat trout populations.

  3. Scotch is not yet known to, but it is in the close neighborhood with those that do and shares with them favorable habitat characteristics.

  4. It would seem wise to include Scotch in efforts to obtain Outstanding Waters designation and protection, looking ahead to the likelihood that the presence of cutthroat trout populations there will be confirmed or may be installed as part of species preservation.

e. Minimizing contention

  1. The 8 streams suggested for highest priority out of 42 represent a minimization of opportunities for contention with existing land and water resource use, with only 3 draining range allocations and only 2 having water diversions, 1 each.

  2. Of the 3 streams draining range allocations, 1 of them, Coal, has grassy streamside grazing, and only at high elevations in the watershed, in a large meadow at approximately 10,000-11,000 ft, which likely minimizes erosion and the addition of sediment to the streambed. (See slide 6 for Coal as compared with slides 5 for Stoner and 10 for Wildcat, both of which have exposed-soil, forested streamside grazing, at Streambed conditions in Gallery.)

f. Favorable features

  1. Barlow, one of the suggested highest priority streams, has a favorable feature in the form of a small lake, referred to as Barlow Lake, and large flood plain just behind a rock dam, upstream a mile and a third from its outfall at the main stem, which contribute to recharge and maintenance of downstream baseflow. (See slide 1 at Watershed features in Gallery.)

  2. Likewise, Scotch has ponds and flood plain, located a little over 2 miles upstream from its outfall at the main stem, established by former beaver activity, which contribute to recharge and maintenance of downstream baseflow. (See slide 2 at Watershed features in Gallery.)

g. Further protection and action

  1. Further administrative protections for the highest priority streams can be considered, for example, to limit decreases to trout populations, such as by managing when fishing is allowed and, perhaps, establishing what gear is acceptable, such as barbless hooks.

  2. The possibilities of science-based actions that could help preserve and even enhance habitat can be investigated, for example, projects that could increase recharge to stream baseflow or manage runoff having constituents that can diminish instream food production, such as excessive nutrient concentrations and sediment.

h. Engagement and input

  1. There are individuals who have historical and ongoing interests in land and water resources in the basin, including property owners and business people, which would be in addition to folks who trout-fish or study it as scientists.

  2. Those individuals with historical and ongoing interests, along with the public, in general, are necessarily part of good, long-term decisions about the resources, portions of which include trout habitat examined and contemplated in this study; and recognition of the need to have their engagement and input is expressed at "C. Outreach" in Stream protection.

Protections underway and stream characteristics

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