Pumpkin Creek LTPBR Phase 1
Bureau of Land Management Partner
Anabranch Solutions Design and Implementation
Project Goals and Objectives
The Pumpkin Creek riverscape is currently degraded as a result of historic land use practices (i.e. extensive livestock grazing and agriculture development) and beaver extirpation. The mainstem channel suffers from incision and lack of geomorphic complexity, such that the fluvial system cannot support healthy floodplain, riparian, or instream habitats. Restoration aims to promote natural, self-sustaining processes such as channel aggradation and widening that allow a healthy, resilient riverscape to develop in the absence of beaver and wood structure. These processes will allow the channel to recover from previous incision and provide higher quality habitat for native fish and terrestrial species. Specific goals associated with the initial phase of this project are: Increase the proportion of active valley bottom, increase lateral connectivity, expand riparian cover along the channel and within active floodplain, increase channel/habitat complexity. This project is ongoing and will be active through the 2024 field season.
Structure Construction Elements
PALS were constructured in the initial construction phase of 2023. Material consisted of ponderosa pine and juniper sourced from a nearby forest plot owned by the State of Montana. Structural material ranged in size between 3 to 8' in length and 2 to 5" in diameter. Structures consisted primarily of channel-spanning and bank-attached PALS with few occurrences of mid-channel PALS. Channel-spanning and bank-attached PALS were built on inset bars to erode existing riverbanks and widen the active riverscape. Mid-channel PALS were built on islands to promote aggradation and develop more complex habitats within the active chanel. Pumpkin Creek is known to have volatile discharges (up to 8000 cfs), so each structure was secured with 6' (2-4" diameter) untreated wooden posts pounded into the streambed using a hydraulic post-pounder. To ensure structures would withstand high flows, between 10 to 20 (avg. of ~15) posts were pounded into each structure.
Project Photos
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