Two tunnels, one or none? The question continues to swirl around plans to perform major surgery on the sickly heart of California's water system.
Confronted with a shortage of funding, state officials announced last month that they would move ahead with the construction of one giant water tunnel under the Sacramento-San Joaquin Delta rather than two.
But the announcement did little to settle the fate of the project, which Gov. Jerry Brown's administration considers vital to sustaining water deliveries to one of the country's richest agricultural regions and the urban sprawl of Southern California.
Opponents still don't like the so-called WaterFix plan, which despite downsizing is massive. Financing remains an open question. And backers haven't given up their dream of two 35-mile tunnels carrying high-quality Sacramento River water under the delta's levee-ringed farm islands to government pumping plants that fill southbound aqueducts.
"We're being sent down a lot of rabbit holes, and we don't know which one's got the rabbit," said Jonas Minton, a former state water official who is on the staff of an environmental group.
Money is the key to WaterFix, a priority of Brown's administration that has been in the planning stages for more than a decade. Underlying that is the fundamental question of the tunnels' value to California's water supply.
The $17-billion bill for the twin-tunnel version was supposed to be paid by the San Joaquin Valley agricultural districts and Southland urban agencies that rely on water deliveries from the southern part of the delta. But the farm districts have for the most part declined to open their wallets, saying the tunnel water is too expensive for them.
That prompted the Brown administration's decision to press ahead with a less-expensive, one-tunnel project. But as the state continues to try and round up enough financing for the scaled-down proposal, the Metropolitan Water District of Southern California is pondering whether to ride to the rescue of the full project.
There is no formal proposal on the table, but the MWD staff is exploring the possibility of the district picking up WaterFix's unfunded portion and building both tunnels.
If that happened, the water wholesaler's tunnels tab would soar to roughly $11 billion, more than double the $4.3 billion the district board approved last fall.
The ever-shifting plans have intensified debate over the size and need for WaterFix.
Environmental groups argue the billions of dollars that will eventually come out of ratepayers' pockets would be better spent expanding regional supplies such as recycled water and stormwater capture.
"Those projects would actually produce new sources of water," said Brenna Norton, the Southern California organizer for Food and Water Watch.
One tunnel with two river intakes would accomplish much of what water agencies hope to gain with a bigger project, according to Jeffrey Mount, a water policy expert at the Public Policy Institute of California.
"We've said this repeatedly: One tunnel performs almost as well as two tunnels," Mount said. "There is a substantial amount of cost associated with the second tunnel, and it is unclear to me that that creates sufficient benefit to warrant it."
State officials say WaterFix is necessary to sustain delta deliveries in the face of tightening environmental restrictions, rising sea level and the potential for a large earthquake that could topple delta levees that keep seawater from contaminating water exports.
Without the project, the state Department of Water Resources predicts delta exports over time will decline by about a fifth, to roughly 1970s levels.
The tunnel project is intended to lessen the ecological impacts of the state and federal pumping operations that draw directly from the delta's southern portion.
The monster pumps are so powerful that they force water channels to run backward, draw the native delta smelt into bad habitat, confuse migrating salmon and upend the natural flow patterns of the estuary system.
Regulators have responded by clamping down on pumping to cap the reverse flows.
By partially supplying the pumps with tunnel water diverted from the Sacramento River in the delta's northern reach, WaterFix is designed to reduce direct withdrawals from the southern delta — and thus head off more pumping restrictions.
But the tunnels won't give the ailing delta and its vanishing native fish what biologists say the estuary system most needs: a lot more fresh water flowing into the delta and out to sea.
"I basically accept the fact that the water is going to go south and to the Bay Area no matter what … that's the political reality," said Peter Moyle, a UC Davis fisheries professor emeritus whose research helped put the once-abundant delta smelt on the federal endangered species list more than two decades ago.
Given that Moyle doesn't expect the delta to get the flows it needs, he says WaterFix could alleviate some of the negative pumping effects. "When you look at all the alternatives, it's the main one that's out there that is a real alternative for management of the system in a way that can benefit fish."
Environmental groups have consistently argued that constructing two tunnels — each taller than a three-story building — would inevitably invite exporters to pull ever more water out of the delta, despite their assurances to the contrary.
"Once these are constructed, the operations will be subject to whatever the politics of the day are," said Minton, senior water policy advisor at the Planning and Conservation League. "It's like giving a teenager the keys to a 400-horsepower Mustang car and telling them only to drive at 60 miles an hour."
Minton's organization and several other groups previously asked the state to consider paring the project to one river intake and one small tunnel, coupled with substantial investments in developing regional water supplies.
That didn't happen. The two-intake, one-tunnel version the state is now proposing would cost $11 billion, a third less than the twin tunnels, and have a capacity of 6,000 cubic feet per second, also a third less than the two-tunnel proposal.
Because more diversions would have to come directly from the south delta if only one tunnel is constructed, "the benefits of the project drop" as well, said MWD assistant general manager Roger Patterson.
According to an MWD analysis, overall tunnel supplies would decline by a third; there would be some reduction in water quality improvements; and some increase in harmful reverse flows compared to two tunnels.
Still, one key number would not change. Overall State Water Project deliveries to MWD and other state contractors that invested in WaterFix would be roughly the same whether one or two tunnels are built.
So why would MWD take on billions more in debt to build a bigger project that wouldn't increase deliveries to its urban customers?
MWD officials say the extra capacity could be used to convey water that the agency sometimes purchases in addition to its State Water Project allocation. And it would give water managers more flexibility in how they run the pumping operations.
The agency also assumes that San Joaquin agricultural districts that don't want to invest in upfront tunnel costs would be interested in buying tunnel capacity once the project is up and running.
"Will there be buyers in the future that would be willing to pay for that?" Patterson asked. "There's a good chance there will be."
If the tunnels aren't built and delta exports drop as the state predicts, the San Joaquin Valley growers who are holding out on paying for WaterFix will suffer the most.
That's because California's new groundwater law will in coming years force farmers to stop overpumping the valley aquifer — their fallback in times of drought and low allocations from the federal Central Valley Project.
"These are very shrewd businessmen and women," Mount said. "They also know full well that this is a negotiation that's going on. If you don't have enough money to build the whole project, we're going to hold out and see if we can get someone else to pay for it."