On a stretch of Sacramento County land where a nuclear reactor once generated controversy and kilowatts in roughly equal measure, construction crews are assembling one of California’s newer utility-scale battery systems. The Sacramento Municipal Utility District (SMUD) is building the Dry Creek Battery Energy Storage System on its Rancho Seco property, a 2,000-acre site about 25 miles southeast of Sacramento that housed a nuclear power plant from 1975 until local voters forced its closure in 1989.
The project, described in planning documents as a 640-megawatt-hour storage facility, is designed to pair with the Rancho Seco Solar II array already operating on the same property. Together, the solar panels and batteries would capture excess midday generation and feed it back to the grid during evening hours when demand peaks and sunlight fades.
What makes the Dry Creek BESS notable is not just its size but how SMUD got it approved. The utility threaded the battery project through an existing California Environmental Quality Act (CEQA) review, avoiding the years-long permitting process that slows most large-scale storage developments. That approach could offer a blueprint for utilities across the country sitting on retired power plant land they want to repurpose.
From voter revolt to solar-and-storage hub
Rancho Seco holds a singular place in American energy history. Its 913-megawatt pressurized water reactor, built by the Sacramento Municipal Utility District in the early 1970s, was plagued by operational problems, unplanned shutdowns, and cost overruns almost from the start. After years of poor performance, Sacramento voters passed Measure K in June 1989, making Rancho Seco one of the only commercial nuclear reactors in the United States shut down by public referendum.
SMUD spent the next three decades decommissioning the plant, dismantling major components, and remediating the land to meet federal radiological standards. The reactor’s iconic cooling towers stood as concrete relics until their demolition in 2020. Once the site was cleared, SMUD began converting portions of the property into renewable energy infrastructure. A solar facility came first. The Rancho Seco Solar II expansion followed, adding photovoltaic capacity and upgrading the on-site substation. The Dry Creek BESS is the latest addition to that sequence.
The property’s existing transmission lines, substation equipment, and grid interconnection points give it a practical advantage over undeveloped land. Building storage where transmission infrastructure already exists eliminates one of the most time-consuming and expensive steps in energy project development.
The permitting shortcut that matters
SMUD filed the Dry Creek BESS as an addendum under SCH No. 2017092042, the same CEQA case number that covers the Rancho Seco Solar II project and substation. Under California law, an agency can modify a previously approved project through an addendum rather than preparing an entirely new environmental impact report, provided the changes do not create significant new environmental effects.
For SMUD, this meant the battery system did not require a standalone environmental review. The utility could rely on site conditions, biological surveys, cultural resource assessments, and land-use analyses already documented in the Solar II record. The result: a dramatically compressed permitting timeline compared to what a greenfield battery project of similar scale would face.
That distinction matters because permitting delays are one of the biggest bottlenecks in U.S. energy storage deployment. A new battery project on undeveloped land can spend three to five years clearing environmental, land-use, and interconnection reviews before a single battery module is installed. By layering storage onto a site that already passed those hurdles, SMUD sidestepped much of that timeline.
The strategy has implications beyond Sacramento. Hundreds of retired coal plants, natural gas peakers, and other decommissioned generators sit on land with completed environmental baselines and existing grid connections. If other utilities follow SMUD’s addendum approach, those sites could become fast-track locations for battery storage, helping states meet clean energy mandates without waiting years for new permits.
How the project fits California’s storage landscape
At a reported 640 megawatt-hours, the Dry Creek BESS would be a meaningful but mid-tier addition to California’s rapidly expanding battery fleet. For comparison, Vistra’s Moss Landing facility in Monterey County holds roughly 1,600 megawatt-hours of capacity, and the Edwards & Sanborn project in Kern County is designed for approximately 3,287 megawatt-hours. California had more than 10,000 megawatts of battery storage installed or under construction as of early 2025, according to the California Energy Commission, making it the national leader by a wide margin.
The project also aligns with SMUD’s own aggressive decarbonization target. The utility has committed to achieving zero carbon electricity by 2030, one of the most ambitious timelines of any large public utility in the country. Battery storage paired with solar generation is central to that plan, because it addresses the gap between when solar panels produce the most power (midday) and when customers use the most electricity (evening).
What remains unconfirmed
Several details about the Dry Creek BESS are not yet nailed down in publicly available primary documents. The 640-megawatt-hour capacity figure appears in project descriptions but has not been confirmed through SMUD’s CEQA filings, interconnection agreements, or published technical specifications reviewed for this report. Until the utility files detailed engineering documents through a regulatory proceeding, the exact storage rating should be considered approximate.
Construction timelines and commercial operation dates are also absent from the available CEQA materials. SMUD has not published a public schedule indicating when the battery system will begin storing and dispatching power. Without those milestones, it is difficult to gauge whether the project is on pace relative to comparable California installations.
The physical relationship between the old reactor footprint and the new battery hardware is another open question. The Rancho Seco property is large enough that the storage system could sit on adjacent parcels rather than directly atop the former reactor pad. Site plans or engineering drawings that would clarify the exact placement have not appeared in the public CEQA record tied to this project.
Despite the locked headline’s reference to a Midwest location, every verified document reviewed for this article places the Rancho Seco site in Sacramento County, California. No Midwest nuclear facility has been linked to SMUD’s Dry Creek BESS in the regulatory filings examined here.
A decommissioned site gets a second act
Whatever the final capacity number turns out to be, the Dry Creek BESS represents something larger than a single battery installation. It is a test case for whether decommissioned power plant sites, with their existing grid connections and completed environmental records, can be converted into storage assets faster and more cheaply than building on raw land.
The same transmission corridors that once carried nuclear-generated electricity to Sacramento homes will soon move solar energy buffered by lithium-ion batteries. For a site defined for decades by a reactor that voters decided they no longer wanted, that transformation is not just procedural. It is a second act, written into the permitting record one CEQA addendum at a time.
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*This article was researched with the help of AI, with human editors creating the final content.
