Check out the PB race report in the racing section. I asked EDR and waterrockets about Lago Vista and they gave some good info. Good luck.
Big descent, tricky interruptors (rollers)
Summary from ElDiabloRojo
Lago is much different than PB or Wallburg. Basically you've got about a 1.7 mile climb at about 5% ave gradient. Then you make a right turn and make a fast descent that is broken up with some really annoying rollers. Just before the finish is a steep little 50m climb then about 100m to the finish. The descent can be a bit dangerous if you are not used to hitting 50mph+ in a group. A couple of years back a cat 5 hit a deer and was air lifted out.