The system that moves water from relatively wet Northern California to arid Southern California is like a superhighway that’s hundreds of miles long, but is slowed by about 40 miles of dirt roads in the middle of it.

That’s how Jeffrey Kightlinger, general manager of the Metropolitan Water District of Southern California, described the state’s main water problem during a media tour Monday of the Sacramento-San Joaquin Delta hosted by MWD and state water officials.

The water agency and the Brown administration are touting a multibillion-dollar project to bypass those “dirt roads” by building a set of massive tunnels underneath the Delta, which is — to continue the highway analogy — the equivalent of a giant interchange.

Currently, water meanders through the area, held back by aging levees, to a pumping station at Tracy, where it is channeled through the agriculturally rich San Joaquin Valley to the state’s southern metropolises, including San Diego. The pumps are routinely slowed down because of disputes over the health of an endangered fish called the Delta Smelt.

The Delta is the West Coast’s largest estuary — a 1,300-square-mile area with waterways, wetlands, islands, orchards, and marinas. The tin-roofed houses, historic mansions, and erector-set-looking drawbridges evoke images of the Louisiana bayous. It’s one of my favorite places on Earth.

If you flip a California map on its side (Pacific Coast at the bottom), the Delta is the low-lying area where water gathers after it flows out of the mountains before it drains out the San Francisco Bay. It has long been Ground Zero in the state’s water wars. The last battle was a losing attempt in 1982 to build a “peripheral canal” around it.

The tunnel plan is so big it might be visible from space, but it doesn’t necessarily promise more water to the south. Instead, the Bay Delta Conservation Plan offers a more predictable water supply by solving the problems that lead to the pump slowdowns.

Supporters say that the tunnels would protect against earthquake risk given that the current levees are poorly engineered and susceptible to devastation. The state can’t afford to do nothing, they argue. But there are plenty of opponents.

“It’s the best science money can buy,” chided Cathy Hemly, of Greene & Hemly farms near Courtland. “I have a sincere distrust about their assumptions.” Her farm will be devastated by the plan, which she sees as the death-knell for the area. She and other tunnel foes followed the bus and politely handed out information at tour stops.

These critics say supporters are scaring the public over earthquakes given that the Delta is not particularly earthquake-prone. They want the state to instead invest in a less-costly process of shoring up the levees.

At one stop, California Department of Fish and Wildlife Director Charlton Bonham acknowledged that there’s lots of uncertainty about how the plan will evolve. “We in the habitat community have never tried anything this big before.”

Uncertainty is a given in huge projects, but locals say they were cut out of the discussions and that they are concerned about a project that treats them, their farms and their towns as a disposable byproduct to advance a greater good.

No one knows what it ultimately will cost, either. State infrastructure projects are notorious for cost overruns. Water users (i.e., ratepayers) would pay for the $14-billion tunnels, but the total $25-billion project depends on a coming water bond and federal funds to pay for habitat restoration.

The first proposed route paid little mind to local concerns. The new route is more sensitive, but still would restore habitat by flooding more than 15 percent of Delta farmland, with eminent domain a possibility for land acquisition.

The tour bus pulled over near Walnut Grove, where officials gathered around a cross channel. Officials seemed oblivious to the historical town up the road — Locke, built in 1915 by descendants of the Chinese immigrants who built the levees.

That was emblematic. In their rush to undertake a big dig, officials are ignoring the region’s heritage and its people. The state needs to fix its water problems, but Delta residents aren’t the only ones who should worry about the tunnel plan.