The power hungry Silicon Valley could be helping Manteca, Lathrop, and Ripon electrical users lower rates. The Santa Clara based Silicon Valley Power Company has inked a 10-year deal to buy hydro power from the Tri-Dam Project that is owned 50-50 by the San Joaquin Irrigation District and Oakdale Irrigation District. That contract is for a higher amount per kilowatt hour than the current deal with an energy firm that expires on Dec. 31.