At the Council’s April 9, 2015 request, the ISRP reviewed the “Rock Creek Fish and Habitat Assessment for Prioritization of Restoration and Protection Actions” and supporting documents for the Yakama Nation’s project #2007-156-00, Rock Creek Fish Habitat and Assessment. These assessment and prioritization documents were submitted in response to the Council’s November 5, 2013 recommendation from the Geographic Category Review that the project proponent submit a“geomorphology and salmonid assessment report to the ISRP.”The project’s overall goal is to improve habitat conditions for steelhead trout (Oncorhynchus mykiss), listed under the Endangered Species Act (ESA), in the Rock Creek subbasin in southeastern Washington, in order to support sustainable populations.
The ISRP recommends that the assessment meets scientific review criteria. The project proponents have addressed the concerns raised in the previous ISRP review and appropriately highlighted the most pressing issue—water availability. The four documents included in the response, along with several appendices, adequately addressed the ISRP’s first qualification. These documents included a review of fish data collected between 2008 and 2013, a review of EDT model runs, a summary of reports about Rock Creek produced over the last several decades, and a Fluvial Reconnaissance Report (FRR) that provides a detailed geomorphic characterization of the lower reaches of the watershed. Together, these reports provide a fairly comprehensive overview of the status of steelhead and stream habitat in this system. The FRR, in particular, was well done. This work combined remotely-sensed data with a detailed field assessment of the physical conditions in Rock Creek within the area that the EDT analysis had identified as the most promising for habitat actions.
As a second qualification, the ISRP requested that the project proponents provide a description of the process that will be used to incorporate scientific findings into a restoration strategy. The FRR provides a high-level description of how improved understanding of conditions in Rock Creek will be used to develop a restoration strategy (illustrated in Figure 117, Page 103). This strategy provides a pragmatic assessment of the enormous challenges associated with steelhead recovery in Rock Creek. One critical issue, addressed in the genetic and FRR report, is that 85% of the adult fish entering Rock Creek are strays from other systems, mostly Snake River stocks. This fact raises issues about the significance of the Rock Creek population to recovery of the Mid-Columbia Steelhead ESU. If further investigation indicates that the Rock Creek steelhead population is supported primarily by stray fish from out-of-ESU populations, this conclusion should be a major consideration in decisions about implementing future habitat restoration actions in this watershed intended to benefit the Mid-Columbia Steelhead ESU. As stated in the FRR:
“At this point in time, active instream investment in habitat actions for steelhead in Rock Creek seems premature. Realistic habitat goals and objectives that account for intrinsic watershed constraints and address the proper hierarchy of population controls should be developed. For example, if the steelhead run is exogenous and sustained purely by annual influx of out-of-basin adults, efforts to enhance rearing or spawning habitat may be superfluous.”
Even if it is determined that a native Rock Creek steelhead population still persists, it is unclear if there are any effective actions that can be implemented to address absence of late-summer flow, the primary factor limiting productivity of the fish. Any restoration plan for Rock Creek must realistically evaluate the feasibility of increasing flow both now and in the future. The lack of high elevation areas to accumulate snow pack, low precipitation, minimal water storage in the basin, climate change, and increasing human water demands raise serious questions about the feasibility of improving this situation. Lack of late summer flow also exacerbates the impact of other factors that contribute to fish mortality, including high water temperatures and predation. Until the issue with summer flow is addressed, it would not seem a wise use of resources to implement any costly habitat manipulations. This concern is echoed in the FRR:
“Given risks and uncertainties associated with channel behavior, ongoing and expected watershed changes, lack of protection of instream flows, and unresolved benefits to Mid-Columbia DPS steelhead, high unit-cost treatments such as ELJs [Engineered log jams] should generally be avoided. More distributed, lower unit-cost treatments may be anticipated to have some short-term success, but their effectiveness will ultimately depend on instream flow protections and proper identification of meta-population relationships.”
