Sally Ann Creek AOP Crossing and Instream Restoration

Sally Ann Creek, a tributary to the South Fork Clearwater River, has lost tributary connectivity through the development of a road system and agricultural practices. The Nez Perce Tribe will replace two passage barrier culverts on Sally Ann Creek in conjunction with instream and floodplain restoration actions immediately upstream of the culvert. The downstream culvert is undersized with high flows overtopping the inlet and flooding nearby infrastructure most years; the inefficient crossing prohibits the upstream stream channel from properly functioning, depositing large quantities of substrate upstream, eroding banks, and threatening to wash out travel ways.



The downstream culvert is undersized, in various states of disrepair, and a failure risk. The bottom section of pipe has detached and lost a section of roadfill when it failed. The bottom of the pipe is rusted through, making conveyance and migration difficult through the structure while posing a failure risk to the road. The objective of the combined project is to open passage for 1.24 miles to all life stages of fish and restore quality habitat in Sally Ann Creek between the culverts.



Between the two existing, culverts, the stream channel has been negatively impacted by upstream land management, recent high flood events and severely undersized crossings. Substrate mobilizes each year during high flows and deposits upstream of the culvert, erodes the streambanks, and causes damage to infrastructure. Installation of instream structures and both constructed and passively formed pools will improve habitat quality and diversity, and construction of two high flow side channels will reduce stream velocities and allow high flows to pass unrestricted through the site, restore sediment sorting, and establish a healthy vegetative riparian zone. Vegetation will be used to stabilize streambanks.

Providing habitat restoration on Sally Ann Creek alongside the crossing replacements will add value to the project by improving passage and habitat conditions simultaneously. Due to the existing conditions, potential habitat for salmonid rearing and spawning is severely limited. The new crossings are designed to restore passage and improve aquatic habitat by reducing sediment sources for all life stages of ESA-listed species in the area. The replacements also aid in restoration of tributary connectivity, opening access to potential upstream quality habitat. Improving the current upstream condition into a more natural floodplain, while restoring natural stream processes and function will directly increase habitat capacity for juvenile life stages of steelhead. Furthermore, the risks of nonperformance include the continued deterioration of fish passage and instream habitat conditions, resulting in increasingly low returns of salmonids, as well as an increasingly high potential of structure and infrastructure failure. If the existing culverts fail, Sally Ann Creek and South Fork Clearwater River would be negatively impacted with sediment and debris. The new structures will pass all aquatic organisms, including all life stages of anadromous and resident fish.