This time, “Chinatown” is fooling itself.

Los Angeles has a long history of water deceptions, a point made famously by Roman Polanski’s 1974 film classic. But the self-sabotage of the city’s latest scheme is a real doozy. L.A. has convinced itself of the hokum that it has all the water it needs.

Let me be clear: L.A. must produce more of its own water for its long-term security. And leading Angelenos are right to ramp up stormwater capture, groundwater clean-up, recycling and conservation so that more L.A. water is local.

But the idea being sold by elites – that L.A. can become completely water self-sufficient — is a fantasy. Producing more local water would be so costly that Los Angeles would be fortunate to get half of its water from local sources in the decades ahead.

Which makes L.A.’s current deluge of self-deception dangerous. Leading Angelenos are broadcasting their self-sufficiency message at a moment when the state is debating a vital plan to shore up a crucial piece of the region’s water supply: the California Delta.

That proposal, estimated to cost anywhere from $10 billion to $30 billion, would construct one or two tunnels to carry Sacramento River water south, thus providing more certainty about the 30% of L.A. water that runs through the Delta.

Delta Tunnels Are Vital to Future of Los Angeles

The project should be a no-brainer for L.A. But few in L.A. are thinking clearly about water. Instead, the city, under Mayor Eric Garcetti—a smooth-talking optimist full of plans and presidential ambition—has believes it can make transformational changes without much trouble.

Such triumphalism is rooted in the city’s recent winning streak: securing the 2028 Olympic Games, rebuilding its schools, reviving South L.A., transforming downtown into a true center, expanding transit, and getting voters to approve major new dollars for housing the homeless.

But water is different. The best example of over-the-top water triumphalism was an L.A. Daily News op-ed by Garcetti. First he framed his drive for water self-sufficiency as a “Mulholland moment,” a strange choice given that William Mulholland ushered in water imports that Garcetti now rejects.

From there, the mayor went off the deep end, blasting the Delta tunnels as somehow unnecessary, even detrimental to the dream of L.A. self-sufficiency, writing: “We will never be able to solve our water needs if we have tunnel vision.” Finally, he wrote of a city that gets 70 percent-plus of its water from elsewhere: “I’m often asked if we have enough water in Los Angeles for our future. And I always answer that we have plenty of water.”

Mayor Garcetti and Others Miss the Point

That’s laughable, but Garcetti isn’t alone in his hubris. The L.A. City Council just voted to oppose the tunnels if they don’t meet certain conditions. That vote reflects fears of local environmental and consumer groups that use the self-sufficiency myth to oppose the tunnels. They have demanded the firing of the L.A. Department of Water and Power’s ratepayer advocate, Fred Pickel, for the crime of saying that L.A. could afford the Delta tunnel.

Leading Angelenos love to warn that the tunnels’ high sticker price would get passed on to ratepayers and property taxpayers. But the truth is that Delta water via the tunnels would be far cheaper than all the expensive new infrastructure needed to make L.A.’s water more local.

And the tunnels are a real project. So far, L.A.’s various sustainability plans rarely if ever mention the massive costs of making water more local, or how the transition would be financed. The plans also ignore the fact that the drought increased L.A.’s reliance on water imports, particularly from the Delta. The combination of that greater dependence on imports — and L.A.’s statements of self-sufficiency — is dangerous. Why should other parts of the state send us water, if our leaders say we don’t need it?

So, my fellow Californians, I hereby apologize for Angelenos’ ingratitude for the water that comes from your communities to ours. I wish I could promise you that we Angelenos will cool the self-sufficiency rhetoric while the state is debating the tunnels.

But c’mon, Jake, you know what town this is.

Joe Mathews writes the Connecting California column for Zócalo Public Square.