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I would suggest the north side of Banks lake. There are a couple of camp grounds that are first come. Its beautiful on the north side of the lake!! And at night its even more cool. I have never fished from shore there since I have a boat but see people all the time doing it. I have caught bass as large as 5 pounds right off the road in my boat in osborn bay. Theres a ton of rip rap along the road with alot of turn offs for fishing. If I were you i would try that. Like I said its awsome up there. You could even go check out Grand Coulee during the heat of the day. PM if you wnat more info. PS. its about a 4 hour drive from Des Moines.
It really depends on what type of fish your after, trout on sun and blue lakes spin rays on bank with some trout. Either way you'll be happy!
I would go to potholes. Not too far, good camping, and great fishing off the dock. You can catch slab crappies and bluegill by the bucketfulls and if the fish arent biting there, you have dozens of other options within 20 minutes of the resort.