Boscolab - thanks for mentioning our Recycled Fish Hardwater Opens!
Most of the events in Iowa are part of the Recycled Fish "On Ice" Tour so I've been to most.
One thing I'll say - there is a difference between a "tournament" and a "derby," so depending on what you're looking for, some events may suit you better than others.
Des Moines Winter Games Derby @ Easter Lake is a derby - you weigh single fish as soon as you catch them, it's a big fish format.
Usually falls on Easter weekend. We throw an Ice Bash the night before, and you should definitely come - it's fun, free, always good door prizes and a silent auction to help support our cause.
The Manawa Winterfest Derby is also a derby - single fish, weigh when caught, big fish format. This one is in Council Bluffs, usually gets 1,000 - 1500 people. Lots of door prizes. We do an ice bash at Hy-Vee the night before and it's also a really fun event, probably our biggest ice bash.
Both of those are inexpensive to enter - $20 or something.
Now if you're looking for a tournament - that's where you'll try to put together a bucket of (live) fish over the course of the day, an actual weigh-in at the end, then one of our Hardwater Opens (Big Creek near Des Moines or Okoboji in NW Iowa) is probably what you're after.
Here's a link:
http://www.recycledfish.org/our-programs/on-ice-tour/hardwater-open-tournament.htmYou're looking at a more limited field - 60 anglers on Okoboji and 50 2-man teams on Big Creek. Entry fee is $55 + $10 admin fee + $5 big fish pot. Those are cash payouts though, with additional prizes as door prizes, etc.
I haven't been to the Rock Creek event (East Central Iowa) but it's been going on for many years, so that says a lot.
Hope that helps!
Teeg Stouffer
Executive Director
Recycled Fish