Therriault Creek is a tributary to the Tobacco River and is located approximately 6 miles southeast of Eureka, Montana. The Therriault Creek Stream and Wetland restoration project is an ongoing cooperative project between the Therriault Meadows Ranch and KRN collaborators that began in 2004.
Eroding banks before restoration. Slumping bank before restoration. Entrenched channel before restoration.
Project History
This section of Therriault Creek was straightened in the 1940s creating an incised stream channel, accelerated bank erosion, and a reduction in fisheries habitat. The stream channel reconstruction portion of the project occurred in 2004 – 2005, creating 9,100 feet of stream channel, which approximately doubled the stream length by increasing meander frequency. The project also created about 55 acres of wetlands.
New channel construction. New channel with habitat structures. New channel through the hayfield. New channel with increased meanders. New channel before revegetation.
Revegetation
Since the initial phase of the project, the KRN has focused on converting the riparian vegetation from pasture grasses to a mosaic of native riparian shrubs and trees. These revegetation efforts have relied on a multi-year, phased approach that uses maintenance, monitoring and adaptive management.
The KRN began revegetation efforts in 2007 with the development of a riparian vegetation plan that can be found here. Revegetation work at this site has occurred in four phases, with work generally beginning at the upstream end of the project proceeding downstream. Annual effectiveness monitoring and maintenance was completed in conjunction with restoration treatments to determine which treatments worked best.
Revegetation begins New plantings protected from wildlife browse Coir log treatment, 1 year old. Coir log treatment after several years Vegetated soil lift treatment, 1 year old. Vegetated soil lift, several years old.
The first phase of revegetation installed a range of treatment types in 2007. The effectiveness monitoring guided the second and third phases of revegetation efforts completed in 2009 and 2010 that occurred primarily in the upper two thirds of the project area.
A 5-year summary assessment was completed in 2012, concluded that the site was trending toward achieving project goals and objectives, but also identified that wildlife browse, competition with weeds and pasture grasses was limiting the pace of recovery. These findings prompted nearly annual herbicide applications, maintenance, and the installation of a 10-foot tall wildlife exclosure fence in 2013 to protect most of the revegetation planting units.
An updated a 5-year riparian vegetation management plan was completed in 2019 that guided the fourth phase of revegetation within the lower third of the project area in fall 2019 that installed three revegetation treatment types to reestablish willows along Therriault Creek.
Natural willow recruitment inside wildlife fence Overhanging vegetation and undercut banks improves fish habitat. Dense willow growth several years old. Improved wildlife habitat.
Partners
The landowners have been ideal partners for this important project. Without their strong commitments to restoration and specific contributions to off-site livestock watering and weed control efforts this project would not have been possible. This project restored channel morphology, re-established wetland conditions, increased riparian vegetation, and improved fish and wildlife habitat. Annual monitoring has been critically important to inform project partners and direct future revegetation efforts for this important flagship project.
