NORTHWESTERN LAKES OF THE UNITED STATES: BIO- 
LOGICAL AND CHEMICAL STUDIES WITH REFERENCE 
TO POSSIBILITIES IN PRODUCTION OF FISH. 
& 
By GEORGE KEMMERER, J. F. BOYARD, and W. R. BOORMAN, 
Temporary Investigators, U. S. Bureau of Fisheries. 
& 
CONTENTS. 
Page. 
Intiqduction 52 
Maps'*...,.., 53 
Soundings 54 
Anchor release 54 
Temperature determinations 54 
'Thermometers used 54 
Bottom temperatures 56 
Samples of water 56 
Apparatus used in obtaining samples. . . 56 
The sampler 56 
Sampling line 57 
Bottles . 57 
Method of taking samples 58 
Methods of analysis of samples 58 
Determination of dissolved oxygen 
by Winkler method 58 
Solutions required 58 
Method of procedure 59 
Calculation of oxygen content. 60 
Determination of carbon dioxide by 
Seyler method 61 
Solutions required 61 
Titration for free carbon diox- 
ide 61 
Determination of fixed carbon 
dioxide 62 
Calculations of carbon dioxide. 62 
Complete analyses of water of five im- 
portant lakes 63 
Net plankton 65 
Method of obtaining and enumerating. . 65 
Physical conditions in lakes 65 
Thermal changes and gas condi- 
tions 65 
Saturation of water with oxygen 70 
Carbon dioxide content 71 
Page. 
Fish in small lakes in Washington and Idaho. 72 
Mackinaw trout 73 
Fish food in certain lakes 74 
Bear Lake, Idaho 74 
Henry Lake, Idaho 74 
Upper Klamath Lake, Oreg 75 
Crater Lake, Oreg 75 
Green Lake, Wash 75 
Lake Mendota, Wis 76 
Lakes in eastern Washington and Idaho 77 
Bear Lake, Idaho 77 
Calvert Lake, Wash 78 
Lake Chatcolet, Idaho 78 
Lake Chelan, Wash 79 
Clear Lake, Wash 80 
Lake Coeur d’Alene, Idaho 80 
Deer Lake, Wash 84 
Hayden Lake, Idaho 84 
Diurnal movement of plankton 
Crustacea 86 
Henry Lake, Idaho 88 
Liberty Lake, Wash 88 
Loon Lake, Wash 88 
Lower Twin Lake, Idaho 89 
Medical Lake, Wash 89 
Newman Lake, Wash 89 
Payette Lake, Idaho 89 
Lake Pend Oreille, Idaho 91 
Priest Lake, Idaho 92 
Silver Lake, Wash 95 
Spirit Lake, Idaho 95 
Sullivan Lake, Wash 95 
Upper Priest Lake, Idaho 96 
Upper Twin Lake, Idaho 96 
Williams Lake, Wash 96 
Wright Lake, Idaho 96 
51 
