I don't think many people know about this info. Cuyamaca lake has a GPS structure map online here.
http://www.lakecuyamaca.org/gps/gps_map.html
Click on the dots and a description of the structure and a picture of it during low water levels shows up. It's pretty damn cool. I think there is around 150 pieces of structure listed. There is suppose to be a even better map of Lake Jennings coming out with much more features(no yaks but nice new rental skiffs). I'm told by ranger Hugh these are the only two lakes in the whole country that have maps that details structure in this way. One could really get dialed in on these lakes. Cuyamaca still suppose to have sturgen too right? Someone needs to organize a trip. They have cabins up there for rent as well.