Tucannon River Habitat Restoration Update

Habitat restoration began in the Tucannon as early as 1997 funded through the Bonneville Power Administrations Model Watershed Program administered in the Tucannon by the Columbia Conservation District. Early restoration actions implemented in the Tucannon included efforts focused on stabilizing the Tucannon River channel and plant riparian habitat.  The actions were a response to poor river channel width/depth ratios and high stream temperature.  Stream temperatures in the Tucannon were exceeding survival tolerances for salmonids measured at Marengo by WDFW early in the 90′s followed by Washington Department of Ecology  starting in 2003 (Water Temperature Charts).1997 Qhut Image a

Due to lack of channel structure  the big floods of record in 1954, 1964 and 1996 played an increasingly detrimental role in shaping the Tucannon River of River of Today.  Following the 1996 flood (~5,000 cfs) many river reaches exhibited rapid lateral channel migration resulting in nearly complete loss of riparian habitat, and poor with/depth ratios (left).  The image on the left was take at the WDFW Hartsock Unit following the 1996 flood  where riparian and soil alike where lost to the scouring of the flood, leaving large exposed coble bars.  Due to the lack of complexity (Large Trees) in the river channel or on the floodplain, flood events would scour new channels quickly scouring away soil, established young riparian forests and property/infrastructure.  The loss of large trees in the Tucannon developed a negative feedback loop where floods would occur preventing the aging of what ever riparian habitat there was and damage properties and infrastructure.  The loss of riparian during big flood events, maintained a young forest stand that had reduced resistance to high energy flood.  The damage to infrastructure lead to management practices which continued to remove large trees from stream perpetuating the problem.  Project 16 transport Eventually, land management turned to the only engineering action known at the time, straightening and shortening the river channel and the placement of river levees.  Constricted floodplains and increased channel slope in the Tucannon has resulted in the development of large continuous sediment transport reaches which provide very little salmon habitat within and cause unnatural deposition below them.  (Left)  Typical transport reach exhibiting poor riparian and low habitat quality.