Pataha Creek Watershed Assessment

The Pomeroy Conservation District completed an assessment of fish passage barriers along approximately 18.5 miles of incised channel within the lower Pataha Creek watershed, between river mile 3 and 22, ending just outside the west city limits of Pomeroy. This assessment was proposed because of the improving conditions in flow, temperature, and sediment in the stream and the increased number of spawning steelhead (>40 individuals). The Snake River Salmon Recovery Board recommended that improved passage into the drainage would warrant an assessment of any limiting factors, such as accessibility of the stream channel. In 2007, a barrier assessment was completed by the Walla Walla Community College that only assessed bridges, culverts, and other road crossings. With the deeply incised condition of the lower Pataha, it was felt that they may have missed a barrier in some of the inaccessible areas.
The original project scope included a low level flight taking a high definition video of the entire 50 mile length of the Pataha Watershed. But the project scope was scaled down because of a multitude of problems, including seasonal weather patterns and the lack of available equipment needed to do the project as planned. It was then determined that a stream walk would be the best option for assessing the stream, but for only the lower portion of Pataha Creek from its confluence with the Tucannon River to the west city limits of Pomeroy. The walk completed under this project assessment concluded that there were no permanent barriers within the assessment reach, but there could be some seasonal barriers from windblown debris that deteriorate over time. During the winter of 2013/14, the district also visited each site that was identified during the WWCC assessment in 2007 (SRFB #07-1881) and confirmed their report. The WWCC assessment identified two culverts in the upper Pataha Watershed as low flow fish barriers. Those barrier culverts are outside the lower Pataha Creek assessment area so no conceptual designs were completed; the District plans to address them with a new application in the next round of applications.
The finished products of this assessment included write-ups, photos and measurements from those involved with the January 2014 stream walk. Each assessment report includes an overview of the current status of the areas walked and, in some cases, ideas on improving some of the problems they observed.
Future work planned in the Pataha Watershed includes a possible project working with Ecological Services to place artificial beaver dams in strategic locations in designated project areas to see if, over time, the streambed can be raised and old flood plain reclaimed. Our upland conservation and riparian restoration projects, such as CREP, will continue to be implemented throughout the entire Pataha Creek Watershed.

The goal of the Pataha Creek Watershed Assessment was to identify fish passage barriers within the lower 25 miles of the watershed.