You're right, there is is a pumped-storage unit in the Big Creek project, which is SCE as you note. It appears to work off of Shaver Lake, with an upper reservoir at Balsam Meadows. Hadn't heard about that one, though Wikipedia claims it was built in the mid-1980s.
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en.wikipedia.org]
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Edison basically owns the San Joaquin River basin above Auberry (Wishon project including Bass Lake is PG&E). PG&E owns the Kings River watershed above Pine Flat Lake, mostly in the Dinkey and Helms Creek watersheds.