Summary Description: Study the effects of changing the winter draw down of Lake Pend Oreille and the Pend Oreille River on warm and coldwater fish and implement necessary changes. Determine other possible mechanisms for fish declines including predation and competition

Background: This project was planned for FY l996 but did not receive funding in the prioritization process.There was a previous study conducted under project number 9503500 and completed in FY1995. Lake Pend Oreille is the largest natural lake in Idaho; 90,000 acres. Sport fisheries in the lake have been severely impacted by hydropower development on both the inflow and the outflow of the lake Since the 1960's, the lake has been drawn down 6 feet to meet the flood control rule curve and then drawn down an additional 5 feet for electric power production. This last 5 feet of draw down has significantly impacted kokanee, predatory fish which feed on kokanee, and warm water fish species in 23 miles of the Pend Oreille River (Maiolie and Elam 1993). This project experimentally raises the lake level 4 feet during 3 winters to determine whether or not lake levels (developing new rule curves) could be used to recover these impacted fisheries. A second part of the project is to determine if predation, competition with shrimp, or competition with hatchery kokanee contributes to the low fish populations.

Milestones: This project has a contract for $315,000 in 1997. Accomplishments: 1997 First year of project. US Army Corps successfully changed winter lake level. Higher lake level added nearly 2 million square feet of spawning gravel to shoreline areas of the lake, but it was too early to have improved kokanee density. Kokanee population was successfully measured by hydroacoustics, trawling and spawner counts. Unfortunately the lake had the heaviest flooding in the last 40 years and dissolved gasses reached 120-130%. All age classes of kokanee declined. Spawning population declined to record low levels. Kokanee spawning activity was mapped on 100 miles of shoreline. Kokanee were documented to have moved into new shoreline areas for spawning. Depths of kokanee spawning were measured. Kokanee were found to have moved on to newly available gravel at shallower depths. The bulk of the kokanee population spawn at a 4 foot depth on the newly created clean gravel. This was a good indication that spawning was improving. 1998 Kokanee population successfully measured by trawling and hydroacoustics. Fry abundance very low. Record low numbers of eggs were laid in 1997 which produced low numbers of fry in 1998. Flooding and high dissolved gas confounded the results of the lake level experiment. Graduate student study successfully shows that newly emerged kokanee do not starve because of competition with Mysis shrimp.

Results: Not recorded

Publications:

Publication Title	Report Type	Coverage Years	Published	Pages	DOE/BP Number
Lake Pend Oreille Fishery Recovery Project	Annual	1998 - 1998	May 2000		00004003-1 R 149
Lake Pend Oreille Fishery Recovery Project	Annual	1996 - 1997	Sep 1999		98065-2 R 154
Kokanee Impacts Assessment and Monitoring on Lake Pend Oreille, Idaho	Annual	1995 - 1996	Sep 1998		98065-1 R 153

Project Classification Keys:
Primary: All projects in the Resident Fish Program
Secondary: Research, evaluation, and studies
Tertiary: Mitigation and recovery planning

Work Sites

Site/Subsite Names	Site Type	Types of Work Performed
UNKNOWN/	Unknown	Undetermined

Project Budget and Obligation:

Fiscal Year	Initially Authorized	Latest Authorized	Authorized Change	Obligation In Process	Bonneville Overhead	Contracted Obligation	Contracted Agent
1997	$315,480	$315,480	$0	$0	$0	$315,480	IDAHO DEPARTMENT OF FISH & GAME
1998	$360,000	$360,000	$0	$0	$0	$360,000	IDAHO DEPARTMENT OF FISH & GAME
1999	$361,000	$361,000	$0	$0	$0	$361,000	IDAHO DEPARTMENT OF FISH & GAME
Totals:	$1,036,480	$1,036,480	$0	$0	$0	$1,036,480	.