Salmon and Steelhead in the White Salmon River after the Removal of Condit Dam–Planning Efforts and Recolonization Results

Abstract

Condit Dam, at river kilometer 5.3 on the White Salmon River, Washington, was breached in 2011 and completely removed in 2012. This action opened habitat to migratory fish for the first time in 100 years. The White Salmon Working Group was formed to create plans for fish salvage in preparation for fish recolonization and to prescribe the actions necessary to restore anadromous salmonid populations in the White Salmon River after Condit Dam removal. Studies conducted by work group members and others served to inform management decisions. Management options for individual species were considered, including natural recolonization, introduction of a neighboring stock, hatchery supplementation, and monitoring natural recolonization for some time period to assess the need for hatchery supplementation. Monitoring to date indicates that multiple species and stocks of anadromous salmonids are finding and spawning in the now accessible and recovering habitat.

Pacific lamprey recolonization of a Pacific Northwest river following dam removal

“…They can climb some structures (Close et al, ; Kemp, Tsuzaki, & Moser, ), but detailed evaluations of their full passage capabilities have not been conducted. There are a series of waterfalls on the mainstem White Salmon River including Husum Falls (Rkm 12.6) Other anadromous fish, including steelhead trout and Chinook salmon O. tshawytscha (Allen et al, ), have rapidly recolonized the basin up to Husum Falls. The occupancy‐based sampling techniques outlined in this study can be adapted to assess potential passage barriers (Jolley et al, ) or within‐basin distribution.…”

“…Condit Dam was breached in October 2011 and was completely removed by September 2012. Sediment from the impounded Northwestern Reservoir was allowed to rapidly flush downstream after the breach and continues to redistribute during high winter and spring flows (Allen et al, ; Wilcox et al, ).…”

Dam removal: Listening in

“…Reservoir erosion may be more rapid and extend farther upstream than anticipated. This was the case during the Condit Dam removal, where unexpected incision of coarse sediment at the upstream end of the reservoir eroded 24% of redds established by Chinook salmon that had been translocated upstream of the dam prior to breaching [ Allen et al ., ]. The breaching of Condit Dam also resulted in unexpectedly high sediment conditions [ Wilcox et al ., ].…”

River response to large‐dam removal in a Mediterranean hydroclimatic setting: Carmel River, California, USA

“…As is typical for Mediterranean‐type rivers, the Carmel River flow varies over more than three orders of magnitude seasonally; all of its sediment‐transport capacity occurs during a winter rainy season, with no secondary contribution from spring snowmelt high flows. The ecosystem composition thus also differed from that in previous studies of large dam removals, which have focused on US Pacific Northwest biotic communities (Tonra et al ., ; Allen et al ., ; Claeson and Coffin, ; Quinn et al ., ). Second, whereas most dam removals release stored reservoir sediment by natural river erosion, the majority of sediment impounded by San Clemente Dam remained sequestered by design after dam removal.…”