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A LIMNOLOGICAL RECONNAISSANCE OF 

 WEST OKOBOJI L,BR.«v 



E. A. BiRGE and Chancey JuDAY -^^^ " '^ 

 I— SITUATION, AREA, VOLUME ^^^^^;-^ 



Lake Okoboji lies in Dickinson county close to the north- 

 ern boundary of Iowa ; it is situated in T. 99 N ; R. 36 and 

 37 W. Its approximate position is lat. 43.35° N; long. 95.13° 

 W. The region adjacent to the lake is thickly studded with 

 other lakes and lakelets. Two lakes of considerable size — 

 East Okoboji and Spirit lakes — are connected with it. Be- 

 sides these there are ten or more bodies of water, which 

 are large enough to bear names, and smaller ponds and 

 pondlets bj'' the score. None of these bodies of water, except 

 Okoboji lake, has any considerable depth. East Okoboji 

 lake reaches a maximum depth of about 8 m. (26 ft.), but 

 most of its area is less than 3 m. (10 ft.) deep. Spirit lake 

 has a maximum depth of 7.6 m. (25 ft.), but much of the 

 area is between 6 m. and 7.5 m (20 ft., 25 ft.) deep. Oko- 

 boji lake has a maximum depth of more than 40 m. (132 

 ft.)^ and therefore differs widely from its two neighbors 

 both in phj'sical and biological characters. 



The following paper records the results of a limnological 

 reconnaissance of the lake, July 28-August 2, 1919. The 

 reconnaissance was made as part of the cooperative work 

 done by the United States Bureau of Fisheries in connec- 

 tion \vith the Wisconsin Geological and Natural History 

 Survey. The present report is issued with the permission 

 of the Bureau. The study was carried on at the Iowa Lake- 

 side Laboratory, to which the authors are indebted for 

 much help and many courtesies. 



1 Dr. Tilton ('16 p. 96) reports a depth of 135 feet But as nothing is said re- 

 garding the calibration of his line, the maximum may still better stand at that found 

 by the regular survey. 



