By the way, the tunnel being proposed is 45 miles long and so wide in diameter (29 feet) that small planes could fly through it.
Maybe the state could sponsor flight competitions to help pay the cost of building the thing. They certainly won’t be able to use it full-time for conveying water. Even Northern California can’t produce 15,000 cfs of water 24/7/365.
And we can create jobs in California for pilots providing tunnel inspection services.