Grant ideas

A. Introduction

Here are four ideas that could be part of discussion about developing proposals to apply for grant funding. All four ideas directly pertain to cutthroat trout habitat, which is a potential priority in proposal evaluation. Three of them would not slow or collect stream flow and so they would not seem to interfere with downstream water rights. The effect of the fourth idea on flow to McPhee Reservoir may well be negligible, but it needs to be considered. None require high technology or heavy equipment to conduct. As well, all could make valuable use of participation by Dolores River Anglers (DRA) members.

B. Using culverts for creating exclusion barriers

A feature of the Cutthroat Conservation Strategy of which Colorado is a party is use of exclusion barriers to isolate cutthroat trout from non-native trout populations.
An example of an exclusion barrier has been installed recently in the upper Dolores River basin, and is a wood-plank barrier placed in a concrete culvert at Wildcat, shown in figure 1.
It would seem to demonstrate the availability of culverts and the simplicity of this type of barrier installation for creating isolated cutthroat habitat.
We have water quality analysis results (for temperature and 12 Outstanding Waters parameters) at 5 tributaries in the Dolores basin in which flow passes through culverts before entering the main stem.
Those streams, in descending outfall elevation, are Snow Spur, Slate, Coal, Scotch, and Priest.
Snow Spur has 2 rectangular, concrete (walls and floor) culverts that are separated in the stream by roughly a half mile.
Scotch and Priest each have a 2-channel rectangular, concrete (walls only) culvert with rock floors.
Slate and Coal each have 2 side-by-side round, corrugated steel culverts.
All of these culverts are relatively near stream outfalls at the Dolores River.
The water quality data collected demonstrate that those streams are suitable as cutthroat trout habitat.
As well, cutthroat trout populations are known to be present in those streams.
This idea would be to do experimental barrier installation at each of those 3 types of culverts (which are all-concrete, concrete with a rock floor, and steel).
Each type has features that present both distinct accommodations and challenges.
Barrier installation at all 3 types is expected to be easier and results be more resilient to damage from erosion than installations in open stream channels.
Therefore, this potentially could be considered relatively low-hanging fruit for barrier placement and testing.
The purpose would be to attempt to demonstrate that it is the case, the simplicity and resilience, for the 3 types of culverts in the Dolores basin.
The results likely would be applicable to other Colorado basins since culvert types are relatively common.
The planning and work would require collaboration with the San Juan Forest Service (SJNF), Colorado Parks & Wildlife (CPW), and Colorado Department of Transportation (CDOT).
Dolores River Anglers (DRA) potentially could assist in the planning, in particular in discussion about the strongest candidate streams for the barrier placements.
For example, DRA can report on stream characteristics that could figure in stream evaluation, such as flow volume, drainage area, maximum elevations, and stream length.
Those features potentially apply to evaluation of relative (among the streams considered) cutthroat habitat volume and anticipated stream resilience.
DRA members might also assist in site preparation, for example, removal of rock and other debris that helps with installation.
Members also could assist with monitoring the results of the installations, for example, barrier physical integrity.
These barrier installations do not need to await removal of non-native trout populations,
That can come later, as conducted by CPW.
Judgements about integrity of the installations could be made, along with advisable modifications, before proceeding with establishing the isolated habitat.
In addition to separating native from wild trout populations, barriers also could prevent warm-water fish from moving from the main stem into tributaries as temperatures rise from climate change.
As well, creating isolated cutthroat populations in headwaters streams, for example, Snow Spur and Slate, could be logical steps toward establishing the upper portion of the upper Dolores basin as strictly cutthroat habitat.
That could be done, for example, with an exclusion barrier at Barlow bridge, which is over the main stem.
It would make East Fork, which is 2nd in largest mean July-August flow (out of 42 perennial, trout-bearing tributaries in the upper Dolores), and Barlow, which is 6th, part of the designated habitat.
They are just upstream of the bridge and do not enter the main stem through culverts.
Slate and Snow Spur, also upstream of Barlow bridge, are 8th and 16th in mean July-August flow.
The wood-plank barrier installed in the concrete culvert at Wildcat is shown below in figures 1 and 2.
Also shown are the concrete culvert with a rock bottom at Priest and an example steel culvert, present upstream at Coal, figures 3 and 4.

Cold-enough | Refuge-reserve | Favorable | Ideas

1 & 2. Looking upstream and downstream at the Wildcat exclusion barrier

3. Culvert with a rock bottom at Priest

4. Round, steel culvert at Coal

C. Testing rock-filled, wire-mesh gabions for exclusion barriers

Exclusion barriers may be judged valuable in upstream reaches of some tributaries.
An advantage may be more difficult access for fishing, potentially reducing stress on isolated cutthroat populations.
An additional advantage may be leaving downstream portions available as refuge for main-stream trout seeking thermal relief during warm-weather conditions, that is, for the downstream portions to function as “off ramps” from the main stem.
East Fork and Bear would be example upper Dolores basin tributaries for consideration, both having water quality data collected that indicate suitability as cutthroat habitat.
The testing would be for barrier success against damage from erosion due to stream flow.
The test initially could be of “speed bump” structures, that is, not creating full-barrier height until experimentation has been completed.
Experimentation could include the gage of the metal grid used, for example, which pertains to both durability and portability.
Experimentation also importantly could be with the setting, for example, (1) with placement between narrow, solid-rock walls, and (2) installation that integrates with more pliable shoreline having movable and adjustable boulders.
DRA could assist in the experimentation with metal grid.
Members also could scout stream channels for candidate installation locations.
This also could include looking for geological barriers that could figure in the best placement of gabion barriers.

D. Using logs and rocks to increase pocket refuge

Potentially important for cutthroat population preservation as stream dewatering increases as a result of climate change are places where trout can go to wait out low flow conditions, which may include periods of flow continuity lost in stream channels.
Therefore, it may be valuable to increase the number and depth of pockets that can serve as temporary refuge.
Refuge effectively is created naturally by logs that fall across streams.
Scouring results as water flows over the logs, particularly during snowmelt, high-flow conditions, resulting in more depth directly downstream of the logs than elsewhere along the stream channel.
This idea would be to harvest and place logs across streams for the purpose of increasing the number of pockets.
It could include removal of rocks and other debris just downstream of the dropped logs in order to increase pocket depth.
Placement of those rocks upstream and against the dropped logs might help hold the logs in place and contribute to scouring by raising water elevation passing over the logs.
In fact, rocks can figure in creating more pocket refuge as part of log placement or in addition to it.
This activity would be in close coordination with the SJNF, ideally using their personnel to do the cutting, for example.
DRA members could assist with log placements and debris management.
Members also could assist with monitoring and documenting the results of the efforts.
Fundamental would be accepting and attempting to maximize natural processes that result from stream flow, that is, natural pocket creation.
It is not expected that this effort would create static, unchanging pocket conditions.
Shown below are examples of pocket refuge created naturally from fallen logs, figures 5 and 6.

5 & 6. Examples of pocket refuge resulting from fallen logs

E. Using BDAs to increase refuge and recharge

Taylor dewatered to dryness for a brief period in 2020, as shown below in figure 7
Flow returned, as did trout, probably restocked from refuge that endured behind a beaver dam seen in figure 8.
During warm weather, flow at Stoner appears to decrease near its outfall, likely due to known diversions just upstream for agricultural use.
A main beaver dam, plus smaller ones, much further upstream at Stoner, however, maintain habitat year-round for trout, including cutthroat, figures 9 and 10.
Current and past beaver-dam activity is apparent at Ryman, beginning near its outfall and extending upstream until the morphology of the watershed narrows.
At least two of the beaver dams at Ryman have resulted in the scouring of deep pockets directly downstream, figures 11 and 12.
An intact beaver dam upstream at Scotch is part of a floodplain area of washed-out beaver dams further upstream, which slow and spread the stream flow, figure 13.
Beaver dams can both create refuge for trout and increase recharge of stream baseflow.
Beaver activity may be encouraged by installation of beaver dam analogs (BDAs), figure 14.
That is, evidence at study areas elsewhere demonstrates that beavers can take over maintenance and further development at BDA locations.
Several BDAs recently have been installed upstream in the West Fork by a private property owner.
None has been placed in the upper Dolores basin on land managed by SJNF, which applies to most of the area draining into the main stem above its confluence with the West Fork.
How much would dams in some tributaries reduce downstream flow?
The mean July-August flow at Scotch, the 10th largest-flow tributary entering the Dolores above the West Fork, is 11.6 cfs, as determined using the U.S. Geological Survey water program StreamStats.
That is, Scotch delivers, on average, a total of 1,405 acre-feet of water to the main stem in that 2-month period.
Scotch is cited because it is an example large tributary, that is, where actions taken could contribute significantly to habitat preservation, and it has prior beaver activity, as indicated above.
The July-August flow at this tributary was selected for consideration because ambient temperatures are highest, meaning lowered flows can expose cold-water habitat to the greatest warming.
So the placement of dams in tributaries, which raise water depth just upstream from them, may be valuable for increasing both thermal and dewatering refuge.
It is reasonable to anticipate that some of the water above a tributary dam will remain throughout July-August, providing refuge, and some will be lost.
Imagine, as a scenario, that 2 acre-feet of water behind a dam in a tributary go to evaporation, evapotranspiration, and subsurface infiltration during that 2-month period.
In this scenario, none of the subsurface infiltration emerges as surface water.
That is, all of the 2 acre-ft of water lost as described above stays lost to downstream surface flow.
For scale, 2 acres is equivalent to 1.5 football field in area, or roughly 100 yards by 100 yards, which is not small.
It could be visualized more in the elongated shape of a stream channel with its adjacent floodplain, and could be 10 yards by 1,000 yards.
A loss of 2 acre-ft would mean a 0.14 percent reduction in water flowing from Scotch into the Dolores River.
It would be a 0.0052 percent reduction in the total flow arriving at the reservoir over that 2-month period.
And it would take a 2-acre-foot loss times 20 (for example, at each of 20 streams) to have a 0.1 percent reduction in the total flow entering the reservoir in July-August.
Again for scale, 2-acre-feet times 20 is equivalent to water a foot deep across approximately 30 football fields.
This scenario is conservative, that is, it overestimates the amount of water reasonably expected to be made unavailable to downstream surface flow as a result of dams in tributaries.
By conservative is meant that most areas collecting water behind installed BDAs likely would be considerably smaller than 1.5 football field.
As well, some portion of the subsurface infiltration at dams is expected to emerge, assisting with stream recharge, that is, not stay lost to surface flow.
And still the loss in this posed scenario, 2 acre-ft times 20, even being conservative, would produce only a small reduction, one-tenth of one percent, in the total flow carried by the main stem to the reservoir in July-August.
Meanwhile, trout habitat in tributaries is being reduced intermittently due to occasions of dewatering from climate change, and that is expected to become more frequent.
Water temperature data collected so far in the upper Dolores basin indicate that tributaries maintain cold-enough water for cutthroat and non-native trout, despite both drought conditions and evidence of problematic temperatures in the main stem.
Finding ways to increase both refuge for trout in key tributaries and recharge of baseflow in those streams undoubtedly will rise in importance in the face of climate change.
An example resource for considering placement of BDAs in the Dolores basin is the Colorado Beaver Restoration Assessment Tool (BRAT).
Developing solutions logically would include engagement rather soon with representatives of SJNF, CPW, the Dolores Water Conservancy District, and landowners with water rights in the upper Dolores, along with DRA members.