​Beaver dam analogs

  B. Beaver dam approach

1. A beaver dam can result in more alluvial water storage and augmented baseflow [1].

2. Beavers do their own maintenance and enhancement of dams.

3. The demise of a beaver colony can mean deterioration and potential loss of impoundment [1].

4. That would continue until a colony is reestablished.

5. Also, beaver presence can have cost, in particular, some loss of trees and shrubs [1].

6. But widened flood plains from beaver dams also can increase the extent of shrub growth.

7. In a wildland setting, beaver activity can have net value. [1]

  C. Variation

1. A beaver dam analog (BDA) simulates beaver activity, and can encourage beaver involvement.

2. “Wherever we put up structures, beavers came and set up shop,” researchers reported [4].

3. A key advantage, a BDA can be placed specifically where damming and impoundment are desired.

4. An example installation is shown above in photo 1 at Bridge Creek in the John Hay River basin in Oregon [5].

5. It was one of a total of 114 deployed to raise water tables and sub-irrigate meadows [5].

6. BDA construction is shown above in photo 2 at Red Canyon Ranch in Wyoming [6].

  D. Authorization​

1. A special use permit may be necessary [7], and certainly comprehensive collaboration with the Forest Service.

2. The construction must "minimize damage to scenic and esthetic values an fish and wildlife habitat...

3. And otherwise protect the environment” [8]. (Federal Land Policy and Management Act)

4. In addition, it should not "jeopardize the continued existence of any endangered species or threatened species...

5. Or result in the destruction or adverse modification of [designated critical] habitat” [9]. (Endangered Species Act)

  E. Application​

1. BDAs may have useful application at upper elevations in Dolores tributaries.

2. In particular, at locations where slope is less and there is space for expansion of flood plain.

3. From higher elevations, BDAs could maximize the effect of baseflow maintenance throughout a stream.

4. Also, at higher elevations there could be less opportunity to interfere significantly with trout movement.

5. Current beaver activity is apparent at Ryman and Rio Lado, and likely other streams.

6. As mentioned above, researchers have found that beavers will follow structure placement.

7. There is no private property that can be damaged by beaver activity upstream in the tributaries.

8. BDA installation could be combined with relocation of beavers from where they are not welcome.

9. Planning would be needed to integrate beavers, including preventing damage to downstream property.

  F. Problem scenario​

1. Another type application could be in direct response to particular experienced problems.

2. For example, Taylor completely dewatered in fall 2020, as seen in slide 10 of Drought flows.

3. Water has returned to the stream and trout have been observed.

4. Little Taylor flows into Taylor approximately 3.5 mi upstream from Taylor's outfall at the main stem.

5. Taylor has a wider and flatter area where Little Taylor joins it.

6. Installation of a BDA there potentially could extend water presence, retaining water from both flows.

7. The result could be pockets of refuge for trout during seasonal dewatering conditions.