PG&E has a conditional OK to drill into Cape Horn Dam on the Eel River, one of two dams it wants to tear down. The holes will test the dam, the ground under it and the river sediment that has built up behind it, according to records filed with state and federal dam regulators. Cape Horn Dam holds back Van Arsdale Reservoir. An intake 400 feet upstream of the dam takes in Eel River water. The water runs through the Potter Valley Project’s tunnels to the East Fork of the Russian River, according to the Federal Energy Regulatory Commission. … In a Sept. 2 letter, PG&E told FERC the drilling is meant “to characterize reservoir sediments as well as to evaluate the Cape Horn Dam embankment and foundation materials in support of the Potter Valley decommissioning.”

Other dam and reservoir news:

• Sacramento Business Journal (Calif.): Sites Reservoir passes major regulatory milestone, still needs to find funding