I've dove all last summer in Lake Havasu....nothing to see....flat bottom, thick mud. vis in june, july was 5 feet if lucky. Now we were in the coves below the city so that might have something to do with it. If your doing a drift dive, the only place I know about for drift diving there is north of the city at a place I think they call Devil's Elbow. You have to be careful of boat traffic but this time of year shouldnt be too bad. Actually the diving was prefect for what we were doing which was practicing running a reel in zero vis. But it did get hard to find things to tie off to...cuz there isnt anything. Very few trees or rocks. We did find 2 one dollar bills, a coleman lantern, a sleeping bag and an couple pairs of shoes though. There are suppose to be some wrecks but we didnt find them.
Have fun!