Suitable locations

  A. Introduction

  1. Pocket refuge may be improved by simple actions taken in the stream at suitable locations.

  2. What are those suitable locations?

  3. They would be where the depth and volume of refuge can be increased efficiently and without adverse result.

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Assessing suitable locations for improving pocket refuge

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  B. Considerations

  1. Potentially favorable locations for improving refuge would have these stream features:

  • Improvable natural pocket

  • Confined width

  • Higher streambed gradient

  • Readily available materials, that is, rocks or wood to add or remove

  • Shade

  • Deeper main path, or thalweg

2. A possible adverse result would be inadvertently backing up and slowing flow in the channel.

3. Best actions would enable access to refuge during low-flow conditions, hence the value of a deeper main path.

4. Streams can be long and productivity is important, so efficient actions would not duplicate existing, sufficient refuge.

  C. Example locations

  1. Photographs below show locations at 6 streams: Coal, Priest, Roaring Forks, Scotch, Stoner, and Taylor.

  2. The favorability of features at those locations for actions to improve pocket refute are briefly assessed.

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Location 1
  • Has an improvable natural pocket, somewhat confined stream width, and available rocks to add for increasing structure height and to remove for deepening the pocket.

  • Upstream gradient change is small.

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Location 2
  • Also has an improvable natural pocket, somewhat confined stream width, and available rocks to add for increasing structure height and to remove for deepening the pocket.

  • Upstream gradient change is greater than at Location 1.

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Location 3
  • Similar favorable features as at Locations 1 and 2, but has a greater gradient change than both.

  • Scouring below a structure due to stream water momentum depends on stream velocity and elevation drop. This location would have greater scouring than at the locations described above.

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Location 4
  • The location is a good example of close-by stream-side shading.

  • There is little gradient change at this location, however, and no natural structure inviting efficiency in improvement action. As well, there is no well-defined main path of stream flow that could minimize connectivity problems between pockets during low flow.

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Location 5
  • Due to the hard-rock streambed, there is no well-defined, deeper path of stream flow. Instead, there is consistently shallow passage of water across the stream width.

  • During low flow, a loss of stream connectivity at this location is possible. It is not a good candidate for actions to improve refuge.

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Location 6
  • Natural pockets appear numerous at this stretch of stream water. The channel is considerably confined and has relatively high streambed gradient.

  • A more productive use of time for improving stream water pocket refuge would be made elsewhere.

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Location 7
  • Beaver activity has created refuge above the dam structure. Trout were observed there.

  • As with Location 6, a productive use of time for improving pocket refuge would be made elsewhere.

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Location 8
  • There is no improvable pocket refuge in this stream stretch, and little elevation change. As well, there is no well-defined, deeper path of flow in the channel.

  • The location is not an attractive candidate for efficient efforts to improve refuge.

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