TABLE OF CONTENTS

 

 

LIST OF TABLES...................................................................................................................... vi

 

LIST OF FIGURES.................................................................................................................... x

 

EXECUTIVE SUMMARY........................................................................................................ 1

 

CHAPTER 1        AN INTRODUCTION TO CLEAR LAKE, IOWA................................... 11

A.     Identification and location................................................................................................... 11

B.     Geological description of the basin .................................................................................... 11

C.     History of Clear Lake and of lake use................................................................................ 12

D.     Comparison of use with other lakes ................................................................................... 13 

E.      Description of Public Access.............................................................................................. 13 

F.      Population and economic characteristics............................................................................. 14 

G.     Valuation of Clear Lake Water Quality............................................................................... 16

  TABLES..................................................................................................................................... 19

  FIGURES................................................................................................................................... 21

 

CHAPTER 2        VALUING PRESERVATION AND IMPROVEMENTS OF................... 26

                              WATER QUALITY IN CLEAR LAKE

A.     Abstract............................................................................................................................ 26

B.     Introduction....................................................................................................................... 26

C.     Survey Design and Implementation..................................................................................... 26

D.     Survey Results................................................................................................................... 28

E.      Conclusions....................................................................................................................... 38

 

CHAPTER 3        ATTITUDES AND PERCEPTIONS REGARDING WATER................. 40

                              QUALITY AND COMMUNITY

A.     Introduction....................................................................................................................... 40

B.     Methods............................................................................................................................ 40

C.     The Lake as a Central Element in the Community............................................................... 41

D.     Organizational and Social aspects of the Clear Lake community.......................................... 43

E.      Water Quality Perceptions................................................................................................. 45

F.      Community Needs As Related to the Lake......................................................................... 46

G.     Opportunities for the Diagnostic / Feasibility Study............................................................. 46

H.     Appropriate Considerations for Future Action.................................................................... 47

 

CHAPTER 4        HISTORICAL CHANGES IN THE CLEAR LAKE................................. 49

                              WATERSCAPE

 

CHAPTER 5        LIMNOLOGY OF CLEAR LAKE.............................................................. 82

A.     Introduction....................................................................................................................... 82

B.     Physical Characteristics...................................................................................................... 82

C.     Historical Data................................................................................................................... 82

D.     Limnological data from diagnostic study.............................................................................. 84

E.      Trophic condition of lake................................................................................................... 87

F.      Algae................................................................................................................................ 87

G.     Macrophytes..................................................................................................................... 87

H.     Hydraulic budget for lake................................................................................................... 88

I.        Lake bathymetry................................................................................................................ 89

J.       Impact of Lake Degradation and Outlook for Lake Improvement....................................... 90

  TABLES..................................................................................................................................... 94

  FIGURES................................................................................................................................... 97

 

CHAPTER 6        ENVIRONMENTAL MICROBIOLOGY AND........................................ 136

                              BACTERIOLOGY OF CLEAR LAKE

A.     History.............................................................................................................................. 136

B.     Seasonal Variation in the Spatial Distribution of Enteric Bacteria......................................... 143

C.     Beach Analyses................................................................................................................. 144

  TABLE....................................................................................................................................... 145

  FIGURES................................................................................................................................... 147

 

CHAPTER 7        PHYSICAL LIMNOLOGY OF CLEAR LAKE......................................... 154

A.     Introduction....................................................................................................................... 154

B.     Methods............................................................................................................................ 155

C.     Results.............................................................................................................................. 158

D.     Discussion......................................................................................................................... 161

  TABLE....................................................................................................................................... 165

  FIGURES................................................................................................................................... 166

 

CHAPTER 8        AN ANALYSIS OF HYDROGEOLOGY, GROUNDWATER................. 180

                              DISCHARGE, AND NUTRIENT INPUT TO CLEAR LAKE

A.     Geology and hydrogeology of the clear lake region............................................................. 180

B.     Estimation of groundwater discharge to Clear Lake............................................................ 182

C.     Estimation of nutrient load from groundwater...................................................................... 192

 

CHAPTER 9        PATHWAYS LEADING TO WATER CLARITY RESTORATION........ 206

                              IN VENTURA MARSH FOLLOWING BENTHIVOROUS FISH

                              REMOVAL

A.     Abstract............................................................................................................................ 206

B.     Introduction....................................................................................................................... 206

C.     Methods............................................................................................................................ 208

D.     Results.............................................................................................................................. 211

E.      Discussion......................................................................................................................... 213

F.      Conclusions....................................................................................................................... 215

  TABLE....................................................................................................................................... 220

  FIGURES................................................................................................................................... 221

 

CHAPTER 10      WATERSHED ANALYSES........................................................................ 232

A.     Introduction....................................................................................................................... 232

B.     Tributary analyses.............................................................................................................. 232

C.     Nutrient and sediment loads............................................................................................... 233

D.     Basin characteristics and sources of impact (nonpoint source)............................................. 235

  TABLES..................................................................................................................................... 239

  FIGURES................................................................................................................................... 247

 

CHAPTER 11      SOIL TEST AND AGRICULTURAL MANAGEMENT.......................... 254

                              PRACTICES SURVEY OF THE CLEAR LAKE WATERSHED

A.     Introduction....................................................................................................................... 254

B.     Methods............................................................................................................................ 254

C.     Summary Results............................................................................................................... 256

D.     Component Conclusions.................................................................................................... 260

  TABLES..................................................................................................................................... 261

  FIGURES................................................................................................................................... 263

 

CHAPTER 12      AN ANALYSIS OF THE FISHERY OF CLEAR LAKE, IOWA.............. 272

A.     History.............................................................................................................................. 272

B.     Strategies for improving fish community and habitat............................................................. 273

C.     Ventura Marsh.................................................................................................................. 273

D.     Mechanical Removal of Carp and Bullhead........................................................................ 274

E.      Biological Control.............................................................................................................. 275

F.      Creating Habitat for Centrarchids....................................................................................... 275

 

CHAPTER 13      SPECIFIC POLLUTION ISSUES AND WATER QUALITY................... 277

                              STANDARDS PERTAINING TO CLEAR LAKE

A.     Point-source pollution sources............................................................................................ 277

B.     Water quality standards from Chapter 61 of the Iowa Administrative Code......................... 277

C.     Toxicity analyses................................................................................................................ 278

  TABLES..................................................................................................................................... 280

 

CHAPTER 14      SUGGESTED RESTORATION ALTERNATIVES.................................. 282

TABLES....................................................................................................................................... 308

FIGURES..................................................................................................................................... 313

 

GLOSSARY................................................................................................................................ 326

 

 

APPENDICES