Reviews, narrative and other documents for proposal

201003800: Lolo Creek Permanent Weir Construction

(View full proposal and assessments at

ISRP final recommendation: Meets Scientific criteria? Yes (Qualified)

from Apr 2010 ISRP 2010-10 report

Narrative and other documents

201003800N.doc (narrative)

ISRP preliminary recommendation: Meets scientific criteria? Yes (Qualified)

This is a fast-track proposal to design and construct a permanent weir in Lolo Creek, tributary to the Clearwater River in north-central Idaho. The weir will be used as a monitoring and evaluation tool to collect adult return information on B-run steelhead (Oncorhynchus mykiss) and spring Chinook salmon (O. tshawytscha). Snake River B-Run steelhead population status and trend data are required under RPA 50.6. The proposal deals only with design and construction of the weir, which will be done by a subcontractor. After construction, weir operation and data collection will occur under the existing NPTH M&E project (198835003), for which a categorical review proposal for assessing steelhead supplementation effectiveness is pending. Over the past seven years the Nez Perce Tribal Hatchery Monitoring & Evaluation project has operated a temporary weir in Lolo Creek. It is intended to serve three primary functions for the Nez Perce Tribal Hatchery program (NPTH; 1983-350-000): broodstock collection, adult monitoring and evaluation, and manipulation/control of hatchery and natural composition of spawners, i.e., exclusion of strays. Current results with the temporary weir, however, seem probably not worth the resources devoted to it. In each of the last several years, it has captured just a few dozen late-moving Chinook and no steelhead. Recently, it has been installed in June and sometimes not until July. The need for a permanent, properly operating weir is clear. The proposal makes the point that Lolo Creek has one of the smaller B run steelhead populations and is therefore more feasible to weir than other situations. Also, there is need to monitor Chinook salmon as part of the supplementation program’s evaluation. Some doubt exists, however, about whether even the proposed permanent weir can function well enough. The proposal states that "given high spring flows and debris load, we anticipate continuous operation of the permanent weir will not be possible over the return period of steelhead." Presumably, this might apply to Chinook, as well. Given that, the proposal could be improved by presenting evidence, such as history of flood timing and duration, about expected disruption of weir operation. Will it, at least in most years, operate properly during enough of the return period to yield an adequate proportion of the run (and if data on individual fish are needed, an unbiased sample), or will it often only catch the tail end of the Chinook run and few if any steelhead, like the temporary weir now does? What has been the success (and failings) of permanent weirs constructed similarly to the proposed weir and installed in similar streams? Will the proposed weir be able to be used to sample out-migrating juvenile steelhead and Chinook? If not, why?

from Feb 2010 ISRP 2010-7 report