Don Pedro is administered by a special district, and it appears to have LEO's like some park districts do. It appears that you cannot carry there:
Don Pedro Recreation Agency
http://www.donpedrolake.com/Recreati...ions/index.htm
New Melones is run by the Feds, I believe (Dept. of the Interior/Bureau of Reclamation. I don't know if the same laws pertaining to caarying with an LTC in national parks and forests would apply there or not.