Some bad dam ideas go to the graveyard, but never really die
Rejected proposals for environmentally harmful, economically inefficient water projects can always be revived when there’s a new subsidy on the table, new crop of legislators in town, or when the latest dry year prompts claims that more dams and canals will solve California’s water problems. (To find out more about water supply alternatives to more dams and canals, click here). This Dam Graveyard tracks the worst of them.
Waking the Dead
Bad ideas for dams can always be resurrected, reimagined or regurgitated. Here are some projects that have begun clawing their way back, through new studies, political backing, or fresh taxpayer subsidies. If we’re not careful, they won’t stay in the graveyard much longer.
Raising Pine Flat Dam – Kings River
In 2024, Congress authorized and funded a study to raise Pine Flat Dam by 12 feet, which would increase water storage by 124,000 acre-feet. That study is now underway, with the allure of generous federal flood-control subsidies that will mask the project’s true costs. A higher dam would shrink one of California’s premier whitewater runs, push the reservoir and its bathtub ring farther into the scenic Kings River Canyon, and crowd the popular take-out beach. All to squeeze a little more water from the already fully-appropriated Kings River. Friends of the River is tracking the Corps study and working with boaters and local advocates to keep this “one last dam raise” from drowning a little more of this stunning Sierran river canyon.
Raising Don Pedro Dam – Tuolumne River
On the Tuolumne River, the Modesto and Turlock Irrigation Districts are pursuing a sweeping scheme to extract nearly every last drop of “unappropriated” water in the Tuolumne River Basin. They’ve applied for rights to 2.7 million acre-feet of additional Tuolumne River water and lined up a package of infrastructure to capture it: raising Don Pedro Dam and Turlock Lake Reservoir, building two large new offstream reservoirs, and constructing a tunnel connection to New Melones Reservoir. The Don Pedro raises are their “low-hanging fruit,” but they would push a whitewater takeout of the magnificent “T” even farther upstream and reduce flows downstream that fish, boaters, and people depend on.
Astonishingly, the higher dam raises being examined would actually – and illegally – drown the reaches of the Tuolumne that were protected under the national Wild & Scenic River Act by President Ronald Reagan. Friends of the River is pushing back against this latest effort to replace what’s left of the living Tuolumne River with a completely engineered plumbing system.
The Slumbering Dead
These are paused or defunded projects that could come alive again in a less river-friendly political climate.
Temperance Flat Dam – San Joaquin River Gorge
This is a proposal to build a 665-foot dam at the upper end of Millerton Lake Reservoir, creating a reservoir stacked on a reservoir. At that height, it would become the second-tallest dam in California. Championed by southern San Joaquin Valley politicians and irrigation districts, the project would drown the spectacular San Joaquin River Gorge, wiping out trails, whitewater runs, unique granite caves, a Bureau of Land Management (BLM) visitor center, and habitat that the BLM has recommended for federal wild & scenic river protection. Despite its massive footprint and multibillion-dollar cost, the dam would have provided very little new water, mostly reshuffling existing water in an already over-subscribed and fully–appropriated system. In 2020, the project’s sponsors walked away after the dam’s state subsidies dried up. They then pivoted their attention to subsidies for reconstruction of the canals that would deliver Temperance Flat Dam and Millerton Lake water. For now, Temperance Flat is slumbering—but we’re keeping an eye out for signs of its revival. Read more.
New Exchequer Dam Raise – Merced National Wild and Scenic River
Below Yosemite, the Merced National Wild & Scenic river flows through a beautiful canyon, garlanded with wildflowers in the spring, before it ends at Lake McClure Reservoir behind New Exchequer Dam. Merced Irrigation District has been promoting a 10-foot raise of the reservoir, which would illegally drown part of the wild & scenic section. To legalize that assault, from 2011 to 2014, local members of Congress repeatedly tried to carve an exception into the 1992 Merced wild & scenic designation (which was signed into law by President George H.W. Bush). Fortunately, national wild & scenic rivers have never been de-designated in order to drown them beneath a reservoir – so far.
To prevent Congress stripping protections away, in 2018 (AB-2572) and 2025 (AB-43) the California legislature strengthened the State’s safety net for federal wild and scenic Rivers. The New Exchequer dam raise has been on ice for a decade—but more dam storage is very popular with some Central Valley politicians. The precedent that de-designating a wild & scenic river would set is concerning enough that Friends of the River and our allies are working to keep this one firmly in the “slumbering” category, if not six feet under. Read more.
Six Feet Under
These are projects that were abandoned when sponsors walked away. We’re celebrating the win but keeping a wooden stake and a shovel handy in case they claw their way back out of the ground.
Prop 1 Dams That Bit the Dust:
Pacheco Dam (South Bay) and Los Vaqueros Dam Raise (Contra Costa County)
A newer, much larger Pacheco Dam was proposed by the Santa Clara Valley Water District (Valley Water) to store water for the South Bay and would have replaced the old, smaller and dam-safety-plagued Pacheco Dam on Pacheco Creek. Water from the new Pacheco Reservoir would have been pumped from the Delta, delivered to San Luis Reservoir, and conveyed by a new conduit and pumped into Pacheco Reservoir. The project was championed as a drought-reliability fix and a potential solution to urban water quality problems from late-season harmful algae “blooms” in San Luis Reservoir. In reality, it would have flooded part of Henry W. Coe State Park, violating California’s strict protections for state parklands. It also would have required massive seismic fixes. As costs exploded from around $1 billion to $2.5 billion, the project’s water became prohibitively expensive even with Prop 1 subsidies. In 2025, Valley Water abandoned the proposal and withdrew its application for Prop 1 funding, but specifically stated they hoped the project would be revived. Read more.
The Los Vaqueros Dam raise was proposed by the Contra Costa Water District (CCWD), with the implied backing of a coalition of Bay Area agencies, to expand the reservoir from 160,000 to about 275,000 acre-feet of storage space. Supporters framed it as a regional water reliability project and a partner-based investment. The raise was relatively non-controversial, compared to most other proposed dam projects. But the project would have delivered costly water, even with nearly half a billion dollars in state taxpayer subsidies. As the price tag soared to $1.6 billion, the multi-agency partnership collapsed, leaving CCWD unwilling to shoulder the risk. With no viable funding path and unappealing cost of water, the expansion was shelved in 2025 and now sits in the graveyard. Interestingly, this reservoir in the Diablo Range had been recently (2012) expanded from its original 100,000 acre-feet to 160,000 acre-feet. The principal purpose of the dam and reservoir is to avoid taking water when seasonal or drought-influenced salinities at the CCWD’s Delta intakes are higher.
Centennial Dam – Bear River
Centennial Dam (originally the proposed Garden Bar Dam) would have created a 110,000 acre-foot reservoir on the Bear River, drowning cherished canyons between Rollins and Combie Reservoirs. Attractive to Nevada Irrigation District (NID) because California water rights law would have allowed it to gain superior rights over existing Bear River users, Centennial failed to win any Proposition 1 statewide taxpayer funding allocations, eliminating an easy path to construction paved with taxpayer dollars. After years of local community opposition and mounting evidence of poor performance and high cost, NID concluded in 2024 that the project wasn’t worth pursuing and recommended shelving it in favor of a small raise of Rollins Reservoir. The District mothballed Centennial and withdrew its water right application—a major victory for local advocates and FOR.