Stage 10 was a true pumped hydro-storage peak power stage, producing up to 11.5 GW electric power for up to 5 hours a day. In stage 11 the flow will be a maximum flow of up to 25,000 cfs, but with periods of less flow during low electricity demand, all to accommodate both water needs and power demands.
The Cove Tank Reservoir dam is 1 mile wide and 250 feet high, the top of the dam is at 4,000 feet. containing up to 60,000 acre-ft of water, enough storage for more than a day’s flow.
The power generating drop is on average (3800 – 2535 – 70×2.2) = 1,111 feet. This stage is capable of generating maximum 2.2 GW of power during peak power demand, adjusted down at low power demand to not exceed the daily water supply.
San Carlos lake is located within the 3,000-square-mile (7,800 km2) San Carlos Apache Indian Reservation, and is thus subject to tribal regulations. It has been full only three times, in 1993 it overflowed the spillway and about 35,000 cfs of water caused erosion damage to natural gas pipelines. The lake contains now (April 6,2021) less than 100 acre-ft of water. All fish is dead.
When the Transcontinental aqueduct is built the lake will always be nearly filled, with flood control nearly automatic, it will never overflow, and it will look like this:
The Coolidge dam will have to be retrofitted for a 25,000 cfs water flow