View the details of the Independent Scientific Review Panel (ISRP) assessment for this project as part of the FY07-09 Solicitation Review.
Assessment Number: | 1994-018-05-ISRP-20060831 |
---|---|
Project: | 1994-018-05 - Asotin Creek Enhancement and Restoration |
Review: | FY07-09 Solicitation Review |
Completed Date: | 8/31/2006 |
Final Round ISRP Date: | None |
Final Round ISRP Rating: | Meets Scientific Review Criteria (Qualified) |
Final Round ISRP Comment: | |
The ISRP recommends the project as fundable with the qualifications that geomorphological watershed analysis and monitoring and assessment results from previous projects be incorporated into the proposal. This qualification applies to both Asotin SWCD projects.
Our qualification to the fundable recommendation is to point to the self-acknowledged "snapshot" nature of the Subbasin Plan, and the lack of geomorphic process analysis that is a crucial part of understanding what should be done where and when to rehabilitate streams in Asotin County. The next review of the Subbasin Plan should include a review of the fluvial geomorphology, as context for proposed actions in the revised plan. Our second qualification is that evaluation of monitoring and assessment of previous projects ought to be submitted prior to the second year of funding. The sponsors need to more fully describe how the efforts to manage and improve the uplands and riparian areas tie into the stream work. It is essential to rehabilitate riparian buffer zones to complement conservation measures in the agricultural areas and in an attempt to stabilize the over-widened creek. The proposers' response indicates clearly that they are relying on the Asotin Subbasin Plan for identification of their proposed projects, as they should be. They mention changes in agricultural practices etc that are in response to the passage in the Subbasin Plan: "Historic and current land use practices have altered the hydrologic cycle of Asotin Creek. Farming, timber harvesting, and urbanization have changed the water cycle, reducing water infiltration and accelerating runoff. To a lesser extent, modifications of the riparian zone, including tree removal, road building, grazing, soil compaction, and flood control projects also altered Asotin Creek hydrology… Asotin Creek is now wider and shallower than it was historically. Changes in the hydrologic cycle are demonstrated by excessive runoff, altered peak flow regimes, lack of ground water recharge, reduction in soil moisture storage, and low late-season flow (Figure 2-3). Stream channel straightening, an increase in slope, and flow velocity have caused a loss of instream fish habitat, especially pools." However, the problem faced in this subbasin is one of recovery from severe degradation, as is clearly stated on p.12 of the Subbasin Plan: "Asotin Creek historically had a less severe gradient, a meandering flow pattern with point bars that formed pools and riffles, and well developed floodplain connections. The point bars provided habitat for an entire aquatic community of plants and animals. The stream channel had long, deep pools and a well-developed thalweg. Today, much of Asotin Creek and its tributaries have been straightened, diked, or relocated. The straight, wide and shallow channel continuously adjusts in order to compensate for alterations to channel shape and location, floodplain disconnections, and modifications to runoff patterns. Flood events in conjunction with these channel modifications have resulted in a braided channel lacking instream structure, pools, and woody riparian vegetation (NRCS 2001). The loss of well developed thalwegs with naturally functioning point bars is responsible for much of the loss of fish habitat." In this situation, rehabilitating existing riparian zones may be necessary while re-establishing the dynamic equilibrium of the channel. This will eventually require redefinition of the riparian zone and the existing work will need to be extended accordingly. Unfortunately, the proposers' belief that riparian zone recovery will lead to channel recovery is unlikely to be borne out, although a dense riparian stand will act to filter sediment leaving the land, or being carried downstream in a flood occupying the floodplain - where it is still connected hydrologically. |
|
Documentation Links: |
|
Proponent Response: | |
|