INTRODUCTION 



This preliminary limnological study of Roosevelt Lake was 

 undertaken by North Pacific Investigations at the request of Mr. 

 Hillory Tolson, Acting Director of the National Park Service to 

 Albert M. Day, Director of Fish and Wildlife Seirvice, December 23, 

 1947, The Park Service, charged with the development of the recre- 

 ational potentialities of Roosevelt Lake, was vitally interested in 

 having good sport fishing in the lake. At the time the request was 

 made, and up to the present time (1949), game fish were and are in 

 small abundance with good fishing scattered and mostly occurring 

 outside the main tourist season. As a first step toward rectifying 

 this situation a thorough survey of the existing fish populations, 

 water conditions and fish food supplies was needed. 



Grateful acknowledgment is due Mr. Claude E. Grieder and 

 assistants of the National Park Service, Lieut. COTnm. J. T. Jarman 

 of the U. S. Coast and Geodetic Suinrey, and Mr. Don Earnest of the 

 Washington State Game Department for their cooperation and assistemcei 



GENERAL INFORMATION ABOUT THE AREA 



Grand Coulee Dam, largest man made structure in the world, is 

 located in the northeastern section of the State of Washington. It 

 is a United States Bureau of Reclamation project which will ulti- 

 mately irrigate 1,200,000 acres of land, and at the present time is 

 a major source of electrical power in the Pacific Northwest. 



Roosevelt Lake, the impoundment behind Grand Coulee Dam is 

 151 miles long and extends north to the Canadiaji boundary. It has 

 an average width of 4,000 feet, an average surface area of 82,000 

 acres, and a storage capacity of 10,000,000 acre-feet. Ihe lake 

 has 600 miles of shoreline of which the greater part has been es- 

 tablished as a National Park for recreational purposes. Unlike 

 most reservoirs the lake has not been drawn down in summer, thus 

 providing more desirable conditions than other impoundments for 

 recreation 8uid the growth of aquatic organisms • 



Source of water supply for the storage reservoir and dam 

 originates in three principal systems: (1), Columbia River proper, 

 which rises in Columbia Lake in British Columbia, flows north- 

 westerly thence south and west around the Selkirk Range and enters 

 the United States in the northeastern corner of the State of Wash- 

 ington Trhere it flows into Roosevelt Lake; (2), Kootenai (Kootenay) 

 Rivor, which rises in British Columbia near the source of the main 



