Summary Description: Conduct study on Flathead River from South Fork confluence to Flathead Lake. Determine effects of flow fluctuations on fish habitat, predator prey interactions, sediment deposition and fish migrations. Link river model to existing reservoir model.

Background: Construction of Hungry Horse Dam on the Flathead River (completed 1952), changed the physical and biological characteristic of the Flathead River downstream. Hypolimnetic releases from the dam artificially cooled the river from 1952 through 1996 when a selective withdrawal structure was installed on the dam, allowing dam operators to control the water temperature in the tailwater. Now that the thermal pollution from Hungry Horse Dam can be mitigated, a primary manageable threat to Flathead main stem health is dam operation. Flow fluctuations from power and flood control operations create an extensive, low productivity, varial zone, greater substrate imbeddedness and species shifts in the aquatic insect community which has become less diverse and less productive. A combination of man-caused factors resulted in the decline in native gamefish species (mountain whitefish, westslope cutthroat and bull trout), and a significant increase in abundance of non-game native species (Columbia River chub or peamouth, northern pikeminnow and introduced rainbow trout and northern pike). This project will use a modified form of the Instream Flow Incremental Methodology (IFIM) to examine the mechanisms by which dam operation affects the riverine community and their environment, and propose operational guidelines to mitigate negative effects.

Milestones: Funding began in 1999.

Results: None identified.

Publications:

Publication Title	Report Type	Coverage Years	Published	Pages	DOE/BP Number
Flathead River Instream Flow Investigation Project	Final	1996 - 2003	Sep 2003		00006358-1 R 230

Project Classification Keys:
Primary: All projects in the Resident Fish Program
Secondary: Research, evaluation, and studies
Tertiary: Impacts and outcomes of various conditions and facilities

Work Sites

Site/Subsite Names	Site Type	Types of Work Performed
FLATHEAD RIVER/UPPER	Stream (river, creek, canal, etc.)	No work done, not funded
HUNGRY HORSE DAM/	Dam (hydro-electric, reclamation, diversion, etc.)	No work done, not funded

Project Budget and Obligation:

Fiscal Year	Initially Authorized	Latest Authorized	Authorized Change	Obligation In Process	Bonneville Overhead	Contracted Obligation	Contracted Agent
1998	$195,600	$199,572	$3,972	$0	$0	$199,572	MILLER ECOLOGICAL CONSULTANTS
Totals:	$195,600	$199,572	$3,972	$0	$0	$199,572	.