TABLE OF CONTENTS
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
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
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