Shasta Dam Raising Project would heighten dam 18.5-feet. (Photo: U.S. Bureau of Reclamation)
Ringside: How to Add 10 Million Acre Feet Per Year to California’s Water Supply
An 18 foot increase in the height of Shasta dam would increase the storage capacity of this massive 4.5 million acre foot reservoir by 600,000 acre feet
By Edward Ring, April 30, 2025 3:52 pm
There is a good chance that a Californian is going to be nominated to become the new Commissioner of the Bureau of Reclamation. One source of opposition to his confirmation could be senators representing states that share with California the waters of the Colorado River, concerned that a Californian will not sufficiently take into account their interests. But if California invests in projects to increase its water supply, it won’t need as much water from the Colorado River.
What follows are ways California, and only California, has the potential to increase its annual water supply by 10 million acre feet per year. That’s enough to cope with a prolonged drought without starving cities or farms of water. It’s also enough to make generous deals with the other states that withdraw water from the Colorado River.
Thin the Water Guzzling Overcrowded Forests
This can be profitably handled by the private sector. Thin our forests back to historically normal levels. A 2011 study by experts from UC Merced reported that 60 percent of the state’s consumptive water comes in the form of Sierra runoff, and that when forest cover is reduced by 40 percent, total runoff increases by an estimated 9 percent. That means if California’s forests were thinned appropriately, 2.2 million acre feet of water (40 MAF x 60% x 9%) would be added to California’s annual water supply.
Dredge the Silt Out of the Delta and Delta Tributaries
If the maximum flow capacity through the delta was increased through dredging, it would be safe to fill reservoirs to higher levels. As it is, water is released from these reservoirs to reserve flood control capacity for a strong late spring storm or an abrupt melting of the snowpack. Resuming dredging of south delta channels, along with tributaries where silt has created flood risk, could allow another million acre feet per year to be retained in California’s reservoirs.
Rewrite the Rules Governing the Delta Pumps
Together, the state and federal pumps situated at the southern end of the Sacramento-San Joaquin Delta have the capacity to move 900,000 acre feet of water per month, but rarely operate at capacity. According to data provided by the California Department of Water Resources, from December 2024 through March 31, 2025, 12.3 MAF flowed through the Delta, but only 1.5 MAF, only 11 percent of flow, was pumped south, only 40 percent of pump capacity. With modifications to operating restrictions, another million acre feet per year can be pumped south from the delta into the state and federal canals.
Build New Infrastructure to Harvest Delta Flows
In an average year over 10 million acre feet of water flows into the San Francisco Bay from the Sacramento-San Joaquin Delta in excess of what is required for ecosystem health. There are many ways to divert more of this water beyond what could be realized from dredging and higher utilization of the existing pumps. The proposed Delta Conveyance would be a 45 mile long tunnel to move water from the Sacramento River north of the delta safely under the fragile delta ecosystem, emerging at the southern end to feed southbound aqueducts. Whether it’s the tunnel or something else, additional ecosystem friendly infrastructure could supply another 1-2 MAF/year.
Expand Reservoir Storage Capacity
An 18 foot increase in the height of Shasta dam would increase the storage capacity of this massive 4.5 million acre foot reservoir by 600,000 acre feet. Another major storage project actually inching towards construction is the Sites Reservoir. North of the delta, this 1.5 million acre foot off-stream reservoir will store water pumped into it from the Sacramento River during high winter flows. Other surface storage projects in various stages of bureaucratic, litigious, or regulatory denial — if not death — include Temperance Flat Reservoir, Pacheco Reservoir, Del Puerto Reservoir, the Los Vaqueros Reservoir expansion, and the Auburn Dam. Expanding surface storage in California is a practical option, offering protection against floods, maintaining environmental flows, and hydroelectric power. Building a few of these projects could yield another million acre feet per year.
Expand Underground Storage Capacity
California’s aquifer storage potential is estimated between 850 million and 1.3 billion acre feet. As it is, farmers throughout the San Joaquin Valley already have distribution canals through which they receive irrigation water allocated each year from the state’s California Aqueduct and the federally operated Delta Mendota Canal. With groundwater pumping now restricted due to dangerously depleted aquifers, farmers have the opportunity to allocate a portion of their acreage to percolation basins that are connected to the existing systems to receive water deliveries in winter and store it underground. Farmers can also divert more Sierra flood runoff to recharge their aquifers. Diverting water when rivers are running high is a cost effective way to recharge aquifers. Apart from aqueduct deliveries, the total runoff into the San Joaquin Valley that isn’t already harvested for recharge but could be is estimated at between 700,000 and 900,000 acre feet per year.
Urban Runoff Harvesting, Wastewater Reuse, and Desalination
A 2022 study by the Pacific Institute concluded that California’s urban “stormwater capture potential is 580,000 AFY [acre feet per year] in a dry year to as much as 3.0 million AFY in a wet year.” The challenge, of course, is whether engineers can design systems to capture whatever the skies deliver. But throughout Los Angeles County and elsewhere, cities are investing in daylighting streams and reducing impermeable surfaces to encourage percolation, in addition to building dedicated percolation basins. It’s making a difference. In the very wet 2022-23 rainy season, LA County Public Works estimated that stormwater capture at groundwater recharge facilities totaled over 500,000 acre feet.
California’s cities are slowly upgrading their wastewater recycling and reuse infrastructure, with Orange County now reusing 100 percent of their wastewater. On the other hand, the 37 wastewater plants surrounding the San Francisco Bay continue to release over 400,000 acre feet per year of inadequately treated water. Not only is this water not captured for reuse, but the discharge nourishes algae blooms that die and turn toxic, with devastating effects on San Francisco Bay ecosystems. Wastewater recycling is expensive but necessary to help downstream ecosystems recover, as well as to provide another source of fresh water.
Which brings us to desalination. Contrary to the perception spread by its opponents, desalination is cost-effective, energy efficient, and can be deployed at a massive scale. Total worldwide desalination capacity is estimated to be 28 million acre feet per year. As for energy consumption, if the 2.0 gigawatts of power generated by the Diablo Canyon nuclear power plant were used for desalination, it would be enough to produce 5 million acre feet of fresh water per year. Desalination is a huge opportunity, and California’s hesitancy to embrace this technology is in conflict with our need for a resilient and diverse water supply, and exemplifies our bureaucratic and litigious paralysis.
Through a combination of urban runoff harvesting, wastewater reuse, and desalination, it is feasible to add another two million acre feet per year, if not more, to California’s total water supply.
Altogether these new water supply projects would deliver the following amounts: forest thinning, 2 MAF/year; dredging delta channels and tributaries, 1 MAF/year; restructured delta pumping rules and new facilities to safely divert flood runoff from the delta, 3 MAF/year; expanded surface storage, 1 MAF/year; additional runoff harvesting from Sierra tributaries, 1 MAF/year; urban runoff harvesting, wastewater reuse, and desalination, 2 MAF/year.
It may be that some of these options do not offer sufficient benefit to justify the cost. But in California’s current political and regulatory environment, none of them are cost effective. And in an appropriately streamlined, deregulated environment, all of them could make economic sense.
One thing is certain. California is the only state in the American Southwest that has the ability to develop another 10 million acre feet of reliable water supply per year. Unlike every other state, where the options are severely limited by geography and climate, in California it is a political choice.
- Ringside: Green Hydrogen in California - May 15, 2025
- Ringside: Saving California’s Rural Water Users - May 8, 2025
- Ringside: How to Add 10 Million Acre Feet Per Year to California’s Water Supply - April 30, 2025
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July 8, 2022
Can you imagine the economic impact that these projects would bring to California and unlike the highspeed rail they would continue to produce real economic impact to California once completed for generations to come. Multiple wins with this list.
I think that if the state would quit dumping dumping all that resevoir water into the ocean it would immensely help. But for some reason the politicians and bureaucracy are purposely starving the state of water, a real good first step would be to boot the politicians and force the bureaucrats into the unemployment line.
At 2.3 million acre feet Auburn dam is no piddling puddle like all th e others listed, except raising Shasta.
California has long since lost the talent to build anything. Since the democrats took control of the ballot system, the state has lived on the investments of the early governors who built the water infrastructure, freeways, education system, etc.
In northern Sacramento country, people swerve around rutted, potholes on crumbling 4 lane intercity roads looking like a bunch of drunks. The only thing that works is a path to reasonably priced college degree so our kids can escape to a job producing state.
Now that California’s glitterati has been torched by Californias incompetence, maybe something will change. I am not holding my breath.
Thanks for the informative article.
Instead of pumping billions of dollars into unreliable windmills and solar farms California should do what France did years ago and develop a series of nuclear generation plants that can double as desalination plants. Build them along the coast where they can create clean fresh water at night when electrical demand is low and during the day make the electricity we are desperately going to need as AI grows.
Yep, after cajoling the voters into approving a gas tax hike to “fix crumbling bridges” and promising to spend it only on roads, they spend it on mass transit, bicycle lanes and walking paths. On a freeway close to where I live, a project rebuilds the perfectly fine median just like it was before instead of fixing the potholes on the far right lane and adding a much needed 4th lane. Those lying, bait and switch a-h’s need to be ejected from sacramento.
Storage is a no-brainer. The tunnel is a high speed train to nowhere on steroids. Desal is expensive and energy intensive which is a severe limitation under the current regime. I think the author should address Trump’s ideas for bringing water for the PNW which could be almost unlimited water.
Yes, refill the aquifers. There were artesian wells in the antelope valley, then the aquifer was pumped down to where it was not economically feasable to grow alfalfa around lancaster. That was before my time, and I’m not young. The Indian Wells Valley was in overdraft 40 years ago. Many years ago I thought that we would eventually need to desalinize seawater and pump it inland. I have no idea of what the potential megawattage would be, but I have thought that at the bottom of the siphons on the DWP aquaduct along the sierras there should be a bypass built, then constructed high enough to avoid flash floods in the canyons, there should be generation facilities installed in the bypassed main line, with the generation either sold to sce or – through the fungibility of electrons, used to power desalination plants on the coast. As a side note, the sce Ridgecrest district is a net exporter of electricity due to thermal generation from the coso area on NAWS at china lake and cogeneration from what used to be kerr macgee in trona. Which tunnel is referred to? I’m thinking of that mass transit boondoggle planned for the hwy 14 corridor. And what is “the PNW?”
Ok, I think I got PNW now, I think a typo thew me – “for PNW” instead of “from the PNW,” implying “coming here from there.” The columbia river is a long, long ways away, the construction cost would be enormous, the planning and permitting would probably take decades, and every inch of right of way would have to be litigated plus fending off all the lawsuits or evironmental oversight bs during construction over trivial things like spitting sunflower seeds on the ground or spilling a half cup of diesel. And all the environmental terrorists filming everything that goes on through telephoto lenses, hoping to catch some peeing on the ground so they can make an issue of it, between peeing on the ground themselves.
Great article, with common sense solutions. Unfortunately, the “environmentalists” will not allow any of them. Their objective in withholding water from the citizens is to turn California, especially the Central Valley, into a desert. Why else would they tear down dams that provide power and recreation, in addition to water for farmers and the rest of us? They are evil, along with most of the legislators in Sacramento, but as long as we allow election fraud, along with ignorant voters, nothing will change. Will Californians wake up before it’s too late? I doubt it.
I think they want to create a famine by killing water to farmd, because when you control the food supply and who gets fed through rationing you control the population. Look at what Stalin did to ukranians when they defied him, and Mao saw the unintended famine he torched off with his economic plan as population control, reducing the mouths that had to fed by not feeding them. It sounds like a conspiricy theory, but I don’t trust the communists in power in sacramento any more than I would Pol Pot and his kmer rouge to run the state.