This is the leverage President Trump can use against liberal politicians in San Francisco. If they persist in having a sanctuary city, President Trump can withhold federal funding to San Francisco and California. If a fight continues, then President Trump can take Hetch Hetchy water away from San Francisco and use it as leverage against them. President Wilson signed the Raker Act in 1913 allowing SF to lease Hetch Hetchy under certain rules, which SF didn't follow. President Trump can sign an order to nullify the Raker Act, breaking the lease. Can be done right after inauguration if he wishes.
Bye-bye water and hydro electricity to SF and surrounding towns until they cave to the feds.
That would be beautiful to see. :-)
Even better! Declare Hetch Hetchy to be a be a national monument and demolish the dam.