200753200 - Molalla-Pudding Sub basin Assessment; utilizing the new EPA Watershed Assessment of the River Stability and Sediment Supply(WARSSS)procedural methods to increase anadromous fish survivability

Sponsor: Molalla River Watch

Short description: The Molalla supports habitat for rearing, migrating anadromous species and resident cuthroat.The impairments within the Molalla River watershed are documented. However, the analysis to identify where to implement on the ground restoration is not developed

Location: Lower Columbia province, Willamette subbasin

Budgets: FY08: $166,217 | FY09: $105,005

Primary species:
Anadromous: Anadromous Fish
Anadromous: Chinook: Upper Willamette River ESU (threatened)
Anadromous: Coastal Cutthroat: Upper Willamette River ESU
Anadromous: Steelhead: Upper Willamette River ESU (threatened)


ObjectiveDescriptionSubbasin planStrategies
Utilize WARSSS to assess 23 miles of the Molalla Within the Molalla, high erosion and destabilized stream banks are releasing excess sediment, causing turbid water and silt deposits that harm aquatic life and violate water quality standards. Although excess sediment impairments are among the most common river and stream water quality problems, assessing sedimentation problems is difficult and tools are limited. The Watershed Assessment of River Stability and Sediment Supply (WARSSS) process, coupled with the ODFW Aquatic Habitat Inventory protocols, provides the analytical tools needed to assess the lower and middle reaches of the Molalla mainstem. WARSSS is a three-phase technical framework of methods for assessing suspended and bedload sediment in rivers and streams (see attached, also see See MainNav.pdf). WARSSS is a watershed approach to sediment assessment and focuses on natural variability in sediment dynamics, geologic versus anthropogenic sediment sources, erosional and depositional processes, prediction of sediment loads, streamflow changes, and stream channel stability, i.e., geomorphic conditions which depart from stable reference conditions. The U.S. Environmental Protection Agency supported the development of WARSSS because there is limited guidance on assessing sediment impairments. WARSSS is used to analyze sediment problems, develop sediment remediation and management components of watershed plans to detail rehabilitaiton project design options. This objective is to utilize WARSSS in order to site specific restoration projects that will gain the most habitat value in a given location. The WARSSS assessment system, when coupled with the ODFW AHI will produce project designs that will enhance the return of the Molalla River to a long term stable condition with emphasis on not only stable geomorphic conditions, but also maximized aquatic habitat. For this discussion a stable river is defined as one that successfully maintains its pattern, dimension and profile, over time while successfully passing its floods and sediment load. This does not mean a channel that is locked into one location, rather a channel that moves at a natural rate within the constraints of a stable mature riparian corridor. Willamette



  • ISRP: Unranked
  • Council: Not fundable
  • BPA: Not fundable