BPA Fish and Wildlife FY 1997 Proposal

Section 1. Administrative
Section 2. Narrative
Section 3. Budget

see CBFWA and BPA funding recommendations

Section 1. Administrative

Title of project
Pahsimeroi River Fish Loss and Irrigation Intake Assessment

BPA project number   5501800

Business name of agency, institution or organization requesting funding
IDFG

Sponsor type   ID-State/Local Agency

Proposal contact person or principal investigator

BPA technical contact   , EWP

Biological opinion ID   

NWPPC Program number   10.2C.2

Short description
Project will determine if losses of bull trout to irrigation diversions on the Pahsimeroi River impact the population. Project will also install and evaluate alternative irrigation intake systems (e.g., filtration) in view of the high costs, construction impacts, operation/maintenance requirements, and vulnerability to ice and flooding associated with drum screens.

Project start year   1997    End year   2001

Start of operation and/or maintenance   2001

Project development phase   IMPLEMENTATION

Section 2. Narrative

Related projects
This project is related to anadromous fish screen projects on the Pahsimeroi River under the Idaho Model Watershed Habitat Project # 9401700.

Project history

Biological results achieved

Annual reports and technical papers

Management implications

Specific measureable objectives
Statistically significant decrease in bull trout and rainbow trout lost through irrigation diversions. Statistically significant increase in bull trout and rainbow trout population size, spawning (redd counts), and increased fry to adult survival.

Testable hypothesis
1. Losses to irrigation diversions do not impact the bull trout population in the Pahsimeroi River.

2. Drum screens are similar to alternative irrigation intake designs in terms of installation, operation and maintenance costs, construction impacts, operation/maintenance requirements, and durability under winter conditions.

Underlying assumptions or critical constraints
Losses to irrigation diversions are limiting the Pahsimeroi River bull trout population.

Methods
The proportion of the bull trout population intercepted, or “exploited”, by irrigation diversions will be estimated by a mark-recapture study. Approximately 250 age 0 fish, assuming 30% interception, and 950 age 1 and older fish, assuming 10% interception, will need to be marked to estimate proportions with 10% coefficient of variation. Fish will be captured with screw traps in the mainstem, marked, released, and recaptured in bypass traps placed in screened diversions. The impact of this source of exploitation on the bull trout population will be modeled with program MOCPOP. Impacts on cutthroat trout, steelhead trout, and chinook salmon will also be investigated. Alternative irrigation intakes will be designed, installed, and monitored at three sites. Data will be collected on costs, construction impacts, operation and maintenance requirements, and durability for comparison with associated drum screen variables.

Brief schedule of activities
Fish loss assessment will occur during 1997. The mark-recapture experiment will be conducted from April through September. Alternative irrigation intake systems will be designed in 1996 and installed in summer 1997 and 1998. These systems will be monitored throughout the year during the period 1998-2001.

Biological need
Losses to irrigation diversions may adversely impact the bull trout population in the Pahsimeroi River. We need to determine if this is the case. If losses are shown to significantly impact the bull trout population, drum screens may reduce these losses. However, drum screens are expensive and difficult to install, operate, and maintain. Alternative irrigation intake systems may be cost-effective substitutes for drum screens.

Critical uncertainties
Preventing the emigration of bull trout into irrigation diversions may not reverse population declines since critical habitats are dewatered in the Pahsimeroi drainage. Irrigators may not be receptive to alternative irrigation intake designs.

Summary of expected outcome
The expected outcomes are 1) irrigation diversions impact bull trout, and 2) alternative irrigation intake systems are cheaper and easier to operate/maintain than drum screens. If the later proves to be true, alternative intake systems may be installed at a greater number of sites. Better coverage of irrigation diversions in the Pahsimeroi River drainage could translate into fewer losses and an increase in the bull trout population. Since cutthroat trout, steelhead trout, and chinook salmon are also prone to interception by irrigation diversions, these species would also be expected to benefit by reducing losses to canals.

Dependencies/opportunities for cooperation
Project is contingent on NMFS/USFS/COE/NRCS/Sho-Ban Tribe consent and/or permits, and the cooperation of irrigators.

Risks
Alternative irrigation intake systems may not effectively deliver water to irrigators.

Monitoring activity
Mark-recapture experiments and/or weir counts will be used to monitor bull trout populations. Costs, installation procedures and problems, operation/maintenance requirements, etc. will be documented for the alternative intake systems.

Section 3. Budget

* For most projects, Authorized is the amount recommended by CBFWA and the Council. Planned is amount currently allocated. Contracted is the amount obligated to date of printout.

Funding recommendations

CBFWA funding review group   Resident Fish

Recommendation    Tier 2 - fund when funds available

Recommended funding level   $181,640