Musselshell Creek Bridge Replacement and Habitat Improvement

Musselshell Creek, tributary to Lolo Creek, provides important spawning and rearing habitat for ESA listed Snake River Basin steelhead. The Musselshell Creek Bridge Replacement and Habitat Improvement project will maintain 31 miles of fish passage (including 5.7 miles of designated critical habitat) while improving instream habitat, floodplain connection, and riparian function for listed steelhead in the Lolo watershed. The current bridge is failing and restricts access to the floodplain. The proposed project will replace the failing 30 log bridge with a 65 bridge with two floodplain culverts. The proposed design calls for replacement of the condemned bridge with a new structure designed to not only maintain aquatic organism passage but also pass large wood and allow for additional floodplain access. The project will also include removal of a ford, channel improvements, riparian planting, and placement of large wood to increase spawning and rearing of native species, especially salmonids. Musselshell Creek is identified as a Tier 1 watershed in the Lolo Creek Atlas. The USFS is in the process of developing a Watershed Restoration Action Plan (WRAP) which would designate the Musselshell watershed as a high priority for restoration.

Maintain access to important spawning and rearing habitat for ESA listed steelhead while restoring in-channel habitat, complexity, floodplain connection, and riparian communities of a Tier 1 assessment unit of the Lolo Creek Watershed. The project will also protect the

significant financial investments over the last 30 plus years on upstream United States Forest Service (USFS), Idaho Department of Lands (IDL), and private property. The current undersized crossing and associated ford have negatively impacted floodplain access, riparian

conditions, and instream complexity. By replacing the structure and removing the ford, Musselshell Creek will have improved conditions for overwintering juvenile salmonids as well as provide hiding cover for upstream migrating adults. The installation of a pair of

floodplain relief culverts will help reconnect the floodplain at high flows and aid in restoration of more natural hydrology as well as establishment of the riparian area.