When I asked for help with Nebraska I got extremely useful answers, so I thought I'd try with Iowa. It is also lacking in info:
I've found that, outside of the few largest cities, information on Iowa sirens is hard to come by. I've searched the forum but still came up with very little. If you have any information about what type of sirens the following towns (or counties the towns are in) use, please post it here.
Adel
Albia
Algona
Allison
Anamosa
Atlantic
Audubon
Bedford
Bloomfield
Burlington
Carroll
Centerville
Chariton
Charles City
Cherokee
Clarinda
Clarion
Clinton
Corning
Corydon
Council Bluffs
Cresco
Creston
Dakota City
Decorah
Denison
Eldora
Estherville
Fairfield
Forest City
Fort Dodge
Fort Madison and Keokuk
Garner
Glenwood
Greenfield
Grundy Center
Guthrie Center
Hampton
Harlan
Ida Grove
Independence
Jefferson
Keosauqua
Knoxville
Le Mars
Leon
Logan
Manchester
Maquoketa
Marengo
Marshalltown
Mount Ayr
Mount Pleasant
Muscatine
New Hampton
Northwood
Onawa
Orange City
Osage
Osceola
Oskaloosa
Ottumwa
Pocahontas
Primghar
Red Oak
Rock Rapids
Rockwell City
Sac City
Sibley
Sidney
Sigourney
Sioux City
Spencer
Spirit Lake
Storm Lake
Tipton
Toledo
Wapello
Washington
Waukon
Waverly
Webster City
West Union
Winterset