Eastwood Power Plant is named for John S. Eastwood, a civil engineer who explored much of the central Sierra Nevada Range with an eye towards Hydroelectric power generation. He discovered Big Creek itself, with its' large water volumes even in summer. The Big Creek Hydroelectric Power Project is called The Hardest Working Water in the World, sometimes passing through as many as 7 powerhouses before being released for irrigation into the San Joaquin River. SCE would even build a common carrier railroad, The San Joaquin & Eastern, to haul materials and personnel into the then - inaccessable Sierra Nevada Range. And it was all privately funded by SCE and its' predecessors.
More information is in the books The Story of Big Creek by David H. Redinger, and The Railroad that Lighted Southern California by Hank Johnston.