(Below is posted in "Ask a Fisherman..." also)
I must admit that I have never fished it....but I have a book called Fishing Man-Made Lakes
that was published as part of the "Hunting and Fishing Library" back in the late '80's early '90's....that has several pages of tips for all species there.
It states that around mid-August bass move back into back-ends of the lower-lake canyons, near milfoil. They recommend poppers and drop-shotting finesse baits near the edges of the milfoil and around stickups.
As the water gets cooler, the bass move out to main lake structure...in depths of 20-45 ft. Pretty much have to jig some type of lure then (spoons - blade baits etc...)...unless you have a arsenal of deep running cranks...or possibly even a s-l-o-w dropped spinnerbait may work.
Also....try this web-forum... www.yumabassman.com
There's a decent bunch of guys there, and the site owner is a Life Member here.
Good luck...and I hope this helps.