Lower Cold Creek Floodplain Restoration
The Coldstream Canyon Watershed Assessment identified floodplain restoration across the lower alluvial fan as a critical strategy to address sediment loading. The Lower Coldstream Floodplain Restoration Project was therefore designed as a two-phase effort. Phase 1, constructed in summer 2012, has successfully withstood
prolonged drought conditions as well as record-breaking flow events. However, the channel immediately downstream of the Phase 1 reach continues to exhibit significant instability, actively eroding the adjacent valley floor. This channel widening is a predictable geomorphic response to historical channelization and,
without intervention, is expected to continue for decades until the channel equilibrates with the floodplain.
Phase 2 of the project builds upon the success of Phase 1 by applying proven, geomorphically based restoration techniques that work with natural floodplain processes to reduce erosion, dissipate energy, and restore channel–floodplain connectivity. This approach accelerates re-vegetation, reduces erosion and sediment delivery, protects existing riparian habitat, and creates additional habitat. Project implementation includes stabilizing actively eroding banks, excavating low floodplain benches within high streambanks, lowering elevated floodplain bars to improve soil moisture conditions for riparian vegetation, and avoiding impacts to well-established riparian vegetation.
The project is fully designed, permitted, and scheduled for construction in 2026, with substantial funding already secured. Additional support from the Truckee River Fund would close a remaining funding gap to restore an actively eroding 300‑foot reach on the left bank using grading, bank stabilization, and installation of a log cribwall. Completing this work would significantly reduce sediment delivery to the Truckee River, enhance riparian and aquatic habitat, and improve long‑term floodplain function and watershed resilience.
TMWA Benefit:
II. Watershed Improvements: The project will decrease sedimentation and support attainment of the 303(d) listed TMDL pollutant to Truckee River. This project also enhances watershed function and habitat within the Middle Truckee watershed by stabilizing eroding streambanks, creating floodplain terraces to reduce velocity and increase inundation longevity and significantly enhancing riparian vegetation.
V. Support to Rehabilitation of Local Tributary Creeks and Drainage Courses: The project will restore a 1,900-foot reach, creating 3.2 acres of new floodplain and increasing riparian habitat by 1.93 acres in a key tributary that is a known source of sediment to the Truckee River. By improving watershed function, this project will help reduce sediment transport to Cold Creek, Donner Creek, and the main stem of the Truckee River.
VI. Stewardship and Environmental Awareness: The project will include outreach to community members through newsletters, email updates and project site
tours. Outreach will be designed to increase understanding and importance of stream and habitat restoration and reduction of sediments and other pollutants within the watershed. Volunteers will also support the project on TRWC’s annual Truckee River Day.