xii Contents 



Lakes Built for Recreation 28 



Planning an Artificial Lake or Pond 29 



Watershed, Run-off, and Water Manipulation 30 



Thermal Stratification and Loss of Oxygen 31 



Seasonal Thermal Stratification 31 



Variations in Thermal Stratification 33 



Fall Overturn 33 



Attempts to Upset Stratification 34 



Thermal Stratification and Reservoir Outlets 34 



Other Factors Affecting Thermal Stratification 36 



Biological Productivity of Water 38 



Lake Size and Productivity 39 



Literature 40 



Chapter 3. Interrelationships of Fishes and Lake Habitats 42 



Sewage Pollution and Fertility 43 



pH and Chemistry of Water 44 



Effects of Water Temperature on Fish 45 



Effects of Turbidity 46 



Oxygen and Carbon Dioxide 48 



Winterkill and Summerkill 49 



Winterkill 49 



1. Aeration of Water Under Ice 51 



2. Aeration of Water Above Ice 51 



3. Pumping of Well Water 51 



4. Snow Removal 52 



5. Lamp Black 52 



6. Circulation of Bottom Water 52 

 Results of Partial Winterkill 53 

 Summerkill 54 



-Other Dangers of Impoundments 56 



Loss of Ponds Because of Burrowing Animals 56 



Wind Action 56 



Dangers from Insecticides 57 



Literature 57 



Chapter 4. Carrying Capacity, Productivity, and Grow^th 59 



Carrying Capacity and Standing Crop 60 



Surface Area 61 



Experimental Testing 61 



Factors Affecting Poundage 62 



Fertilization 63 



