The idea is to build two enormous tunnels, each four stories high and 40 feet in diameter, for 35 miles under the delta, through which about half of California’s drinking water flows.

“This project has been subjected to 10 years of detailed analysis and more environmental review than any other project in the history of the world. It is absolutely essential if California is to maintain a reliable water supply,” Brown declared in a formal statement issued on Dec. 22, 2016.

In the wake of the Oroville dam near-disaster, a question floating around Capitol corridors now is: Given the amount of money needed for what everyone agrees must be an expensive revamping of the state’s water infrastructure, is there room now for Gov. Jerry Brown’s heart’s desire — the $15.5 billion twin tunnels project?

Brown’s legacy proposal is the most ambitious water project California has seen in more than 50 years.

It’s also not the first time he’s sought a major plumbing change in the Sacramento-San Joaquin River Delta: His plan during his earlier years as governor to build a 42-mile-long canal around the periphery of the delta was approved by the Legislature but rejected by voters in a bitter 1982 referendum.

No one believes California can manage water infrastructure improvement and repair without federal help.

But state political leaders have not been shy in their contempt for all things Trump.

How the president will view the state’s need for bountiful federal dollars as part of any water infrastructure improvement program is an open question. Trump did, however, quickly approve a request from Brown to make federal disaster assistance available to California in the wake of the Oroville dam near-disaster.

Brown’s latest idea is to build two enormous tunnels, each four stories high and 40 feet in diameter, for 35 miles under the delta, through which about half of California’s drinking water flows. The watery superhighway would send fresh water from the Sacramento River to cities and farms to the south.

It would not be a statewide obligation. The agencies that reap benefits from the project would pay for it with revenue bonds, with the money coming from the farmers and urban water users in their agencies’ jurisdictions. Financing would not require a statewide vote on a bond issue, although twin tunnels water recipients would presumably be in line to bear some of the cost of statewide water infrastructure improvements in addition to their Twin Tunnels cost.

In 2014, voters approved a $7.5 billion water bond, including $2.7 billion for storage projects,

The plan is opposed by the fishing industry in the north and by some environmental groups who fear that too much water would be sent south, thereby removing a fresh water buffer and allowing more salt water intrusion from San Francisco Bay.

The opponents also talk of the idyllic Delta landscape and the rich farmland, which, they argue, would be endangered by the project. In their view, Southern Californians are in effect saying, “idyllic schmydillic — send the water. Lots of it. Right now.”

California’s water infrastructure of dams, aqueducts, levees and more is big. The California Aqueduct alone is more than 400 miles long, pushing Northern California water south; California has 1,400 dams, some 6,000 miles of levees in the Central Valley — and nearly 39 million people.

Californians have not entirely neglected their water situation. In 2014, voters approved a $7.5 billion water bond, including $2.7 billion for storage projects, to provide funding to water projects and programs.

But the American Society of Civil Engineers says it will cost $65 billion a year over the next 10 years to fix California’s overall infrastructure — roads, bridges, dams, etc. And that’s from a report that is now more than four years old. (The engineers will issue a new report on March 9.)

The Sierra snowpack is at 185 percent of normal — a warm spring could trigger a quick melting, and more flooding.

The engineers said this in their 2012 “Report Card” on California’s overall infrastructure needs:

“In 2012, the 10-year total unfunded infrastructure investment required has increased to $650 billion In 2006, California voters passed almost $42 billion worth of infrastructure measures on the ballots, and although that was a good start and it has certainly helped at least maintain or in some cases improve the grades, the 2006 ballot measures represent only a drop in the bucket compared to the $650 billion needed to move California in the right direction.”

Even accounting for engineers’ characteristic desire to make everything as well done and complete as possible, it is clear that big sums are going to be required.