Solution to California’s water storage needs lies underground, not more dams | Opinion

The name isn't printed on any map, but history-minded visitors to San Luis Reservoir outside Los Banos call it "President's Hill."

In August 1962, on a hilltop overlooking the western shoreline of what today is California's fifth-largest reservoir, President John F. Kennedy headlined a list of dignitaries gathered for the groundbreaking of B.F. Sisk Dam.

Flying to the ceremony by helicopter from Yosemite, Kennedy lauded the state and federal partnership created to fund and operate the new storage site and stressed the importance of managing California's water supply for the benefit of cities, agriculture production and natural resources.

"There is no project in the history of the United States where a state has put such a large contribution to the development of its own resources, and where the national government has joined with the state," said Kennedy, who traveled to Fresno for his next speech.

"This has brought your state to be the pioneer in the United States in the field of development and conservation of our resources. California, in this area, is No. 1, and it has helped make possible this San Luis project, which joins all of us together as full and equal partners."

"President's Hill" is currently closed to the public – and will be until 2032 – because that section of the state recreation area is a construction zone . Gone are the fishermen, campers and hunters. Instead, the roads are traveled by heavy machinery and trucks transporting rocks, gravel and dirt to fortify and raise the 3 1⁄2-mile-long earthen dam and better protect nearby communities from flood risk.

On top of that, literally, negotiations are underway to raise the dam an additional 10 feet in order to create an additional 130,000 acre-feet of storage in the 2 million acre-foot reservoir.

Each project costs roughly $1.1 billion — with about $450 million of the expansion project allocated toward highway construction that will result in lane closures on 152 below Pacheco Pass for up to one year in 2028.

View from 'President's Hill'

When I arranged a tour of the dam site with the Bureau of Reclamation earlier this summer, the first place project manager Henry Garcia drove us to was "President's Hill."

Six decades later, the wooden grandstand erected for the groundbreaking ceremony is long gone. There's nothing up there, not even a commemorative plaque.

Such a plaque would be fitting, because in many ways San Luis represents the last hurrah of California's reservoir boom. (Apologies to New Melones and Don Pedro, which came later. Sites Reservoir, north of Sacramento, is not yet a reality.) San Luis provides water from Sierra snowmelt to Silicon Valley faucets and San Joaquin Valley farms via canals and aqueducts that belong to separate state and federal water projects.

Its reputation as "the linchpin" of California's water system south of the Delta is well-earned.

But while standing atop "President's Hill" it occurred to me how the mindset espoused by Kennedy in 1962 hasn't changed much. This outdated notion that water is best banked behind dams.

California needs more water storage. Few would take issue with that statement. However, constructing new dams or raising existing dams (in most cases) is not the answer.

"It's using 1950s technology to try and fix 21st century problems," said Patricia Schifferle, director of the water consulting firm Pacific Advocates. "There are much better ways to store water than pour a bunch of concrete into the ground and hope you get some."

Drawbacks to dams

Before exploring those ways, let's start by going over the drawbacks to traditional dams. First, they're extremely expensive to build. Sites Reservoir, a slightly smaller northern version of San Luis that has been kicking around since the 1950s , is projected to cost $4 billion.

Second, dams are environmentally destructive. No Californian should be proud that we've created bathtub rings around so many of the state's beautiful, geologically unique river valleys. The third is evaporation. Every year, billions of gallons of water stored in our reservoirs is lost to the sun – and that figure keeps increasing as the planet gets warmer.

The fourth reason also revolves around climate change. In future decades, California will receive more rain and less snow while fluctuating between atmospheric rivers and extreme droughts . "Weather whiplash" is the popular term.

Any water infrastructure built for the 2020s and beyond must adapt to the new climate reality.

So where should California store water for the dry times? The simple answer is underground . Where it can be tapped when needed and in the meantime replenish aquifers that have been depleted from overpumping.

There's also a lot more potential space. The state's underground storage capacity is estimated to be between 850 million and 1.3 billion acre-feet — significantly larger than the combined 50 million acre-feet in above-ground reservoirs.

Groundwater recharge isn't a new concept, of course, but this needs to go far beyond a few scattered basins. The solution calls for massive water banks like the one built by the Metropolitan Water District of Southern California in the Mojave Desert near Lancaster.

Constructed for $211 million, the High Desert Water Bank is connected to an aquifer that has enough space to store 280,000 acre-feet of water. That's more than twice the storage of the San Luis dam raise, at one-fifth the cost .

Fresno's underground tunnel

In Fresno County, there's the potential to make that project seem like a drop in the bucket. That's because we live above an ancient river channel whose existence could tap the full potential of underground storage.

Called paleo valleys by scientists, these tunnels carved by melting glaciers are filled with coarse gravel and sentiment, which makes them more porous than surrounding clay. Sort of like fast lanes for recharge.

As it happens, the first and longest paleo valley ever discovered, by UC Davis researchers using 3D mapping, runs 29 miles from Centerville to Easton.

"If you're looking for a place to put recharge waters and have a big impact, have a big bang for your buck, those would be ... Easy Street locations," said Dr. Graham Fogg, a professor of hydrology.

In other words, a major piece of our water storage puzzle during climate change (along with conservation and recycling) is practically beneath our feet. This is the future. Dams represent the past.