The diets of carp from these two places could not be more different. The Columbia River is full of freshwater clams and a carp on it's nose is sifting through the gravel and silt is looking for these small shelled creatures to dine on along with the occasional aquatic worm. The carp that cruise the islands of the Beaver Archipelago are on a different program and the mainstay of their dinner plate involve chowing down on large crayfish and goby fish that hide in the rocks.
To target the Columbia River carp it takes an exact presentation and the technique that I was taught was to use two flies and try to have them land on the bottom so there is a fly on each side of their face as they would slowly cruise by or if they were tailing. Flies of choice were the John Montana's Hybrid Carp Fly and McTage's Trouser Worm though a double Hybrid rig of two flies of slightly different sizes was a favorite combo. Flies are presented and not moved since when was the last time you saw a clam make a quick escape? These carp are tough but if you make the right presentation and they see one of your flies, I found that they will make the move to suck it up. The presentation, the first time, is everything.
The Lake Michigan island carp are a totally different story entirely. The flies are much bigger and the norm is a crayfish or goby pattern an inch and a half to three and even four inches or more in length. These are big flies with rubber legs and lead eyes to get them down quick. Casts are well ahead of the path of a carp to give time for the fly to drop and settle in on the rocky floor. As the carp gets within range the fly is then moved across it's face with a series of short strips to get it's attention. This often time causes a feed or flight scenario with some carp quickly moving away from the fly, sometimes being indifferent and cruising on, and if you're fortunate, the carp will quickly turn to chase down the fly.