ORGANIC CONTENT OF LAKE WATER 
<&• 
By EDWARD A. BIRGE and CHANCEY JUDAY 
Wisconsin Geological and Natural History Survey 
CONTENTS 
Page 
Introduction 185 
I. — Data 186 
Dissolved organic nitrogen and or- 
ganic carbon 186 
Ether extract 191 
Plankton 193 
II. — Discussion of the data 194 
Organic nitrogen and organic carbon. 194 
Page 
II. — Discussion of the data — Contd. 
Total organic content 196 
Total organic matter, including fats. 198 
Nature of the dissolved organic 
matter 201 
Summary 203 
Bibliography 204 
INTRODUCTION 
For many years the Wisconsin Geological and Natural History Survey has been 
engaged in studies on the inland lakes of the State. These have received aid from the 
University of Wisconsin and the United States Bureau of Fisheries, whose assistance 
is gratefully acknowledged. 
This paper brings together the results of several investigations on the quantity 
and kinds of organic matter found in lake water. In these, as in earlier studies, by 
far the largest amount of attention has been given to Lake Mendota, on whose shore 
the University of Wisconsin is situated. The study has been extended to other lakes, 
in as great number and variety of type as practicable, in order to ascertain how far 
the conditions found in Mendota are present elsewhere. 
The present paper reports results from 14 waters other than Lake Mendota, 
including 12 lakes and 2 rivers. It shows the total amount of organic matter con- 
tained in the water and gives some idea of the nature of the organic compounds. 
Thus it furnishes the beginnings of an inventory of the primary food supply of the 
inland lakes. The results from the lakes other than Mendota are such as to show 
that this may be regarded as a typical Wisconsin lake. 
185 
