84044 REL 13

1996-077-02 EXP LOLO CREEK WATERSHED RESTORATION

2/1/2023

1/31/2024

29. Increase Aquatic and/or Floodplain Complexity

Work Element Usage Report

G: 29 - Construct Beaver Dam Analogs and/or PALS in Jim Brown and Musselshell creeks

This restoration opportunity was identified collaboratively in 2019 during the development of the Lolo Creek Atlas and is based on the most current fish and physical habitat data. It is a high priority for steelhead and lamprey spawning and rearing within Musselshell Creek, which is a Tier I Subwatershed.

Musselshell Creek suffers from chronic, long-term fine sediment aggradation and high cobble embeddedness. Lower reaches of Musselshell Creek are bordered by meadow complexes, which in many years suffer from a lowered water table. Channel incision is a result of historic land use in the meadow (i.e., grazing, areas of timber harvest upstream, and channelization resulting from historic construction activity). Past land use has led to diminished riffle-pool sequences in the creek and overall deteriorating fish habitat.

The sediment in Musselshell Creek is the result of unique geology coupled with a long history of resource management in the drainage. There is currently a limited amount of large wood available for natural recruitment because of several large scale fires in the area in the mid - 1930s, in combination with legacy timber harvest.

In order to restore stream and riparian function within Musselshell Meadows, the Nez Perce Tribe, in partnership with the Nez Perce-Clearwater National Forest, will install approximately 9 beaver dam analogs and/or PAL's in Musselshell Creek as well as approximately 9 beaver dam analogs and/or PAL's in Jim Brown Creek. The structures are designed to function to impound water during moderate flows, create scour pools, redistribute sediment, and improve channel complexity for fish spawning and rearing habitat. The intent of the project is to mimic natural conditions created by beaver dam construction and their effects on stream geomorphology, and to encourage beaver occupation of the structures. There are beaver present at the lower end of Musselshell Meadows.

The structures on Jim Brown Creek will redistribute sediment and improve channel complexity for spawning and rearing habitat for 0.21 miles of Jim Brown Creek. The structures on 0.5 mile stretch of Musselshell Creek will function during moderate flows to scour pools, redistribute sediment, and improve channel complexity for spawning and rearing habitat. A total of approximately 18 BDA and/or PAL structures will be placed in Musselshell and Jim Brown creeks.

The posts will be installed using a hydraulic post driver. Native vegetation (willow or alder cuttings) will then be woven in-between the posts to create in-stream structures that will recruit additional vegetation and organic debris. The wood structures will be placed so as to mimic natural structures (beaver dams or large wood) already present in Musselshell and Jim Brown creeks below the project reach. All work will be done by hand using a hydraulic post driver, chainsaw, and hand tools with access to the project sites by foot across the meadow.

Structures will be located so as to use existing in-stream features such as logs or rocks, and in areas where they are likely to produce the desired effects.
• Structures will be located in a stream reach well away from infrastructure such as roads or trails.
• Project monitoring will include pre- and post-stream cross section and long profile surveys, photo points, and Wolman pebble counts to estimate substrate change.
• Project work will take place during the instream 'fish window' between July 15 and August 30.

Nez Perce Tribe Watershed personnel will install the structures and will monitor the effectiveness of the structures for changes to instream conditions for two years, post-installation, and after any high flow events that may occur in subsequent years.

The Jim Brown BDAs are located on private land and were covered by the HIP programmatic in contract 87084.

USFS completed the analysis and EC on the Musselshell portion of this project in their 7/10/19 Decision Memo process. Copies of EC documents are on file with the BPA's EC lead.

NPT personnel will install up to 18 structures using un-treated posts and locally gathered plant materials to create smaller in-stream structures to help scour pools and redistribute sediment to provide more complex and usable habitat within the channel.

$40,000

6.12%

02/01/2023

01/31/2024

08/15/2023

Concluded

[Unassigned]

[Unassigned]

Finite