EPA cleanup schedule advances at Southwest Superfund sites
The Environmental Protection Agency is moving toward early-August soil cleanup at the Argonaut Mine Superfund site in Jackson, California, where contaminated soil is scheduled to be removed from 39 residential properties and replaced with clean soil.
The work is part of a broader Pacific Southwest construction schedule EPA announced July 16, 2026. The agency listed construction starts at six Superfund sites from July through fall, followed by a later project in Arizona. The schedule places long-planned work on residential soil, groundwater, mine waste and drinking-water protection into the field-work phase, although the announcement does not mean every listed project had already begun.
Residential cleanup in Jackson
EPA says the Argonaut Mine work is intended to reduce residents’ exposure to heavy metals including arsenic, lead and mercury associated with historic mining. The immediate project involves residential yards rather than only additional study or planning.
EPA’s official Argonaut Mine document index identifies a collection for the “2026-2027 Argonaut Mine Residential Non-Time Critical Removal Action.” The July 16 construction schedule refers to 39 residential properties, while a separate Argonaut planning record refers to a 40-property cleanup document. Those figures should not be treated as identical records.
As of Aug. 5, 2026, EPA has not confirmed that the Argonaut work is complete. Residents should watch the agency’s site page, community notices and local information repository for property-specific access, excavation, sampling and clean-soil replacement updates.
Several types of contamination
The regional schedule covers different contamination problems and cleanup methods. EPA listed work at Northeast Church Rock, Lava Cap Mine, Southern Avenue Industrial Area, San Fernando Valley Area 1 and Sulphur Bank Mine. Iron King in Dewey-Humboldt, Arizona, was listed for later in 2026.
At the Southern Avenue Industrial Area in South Gate, California, EPA expects to remove more than 3,000 cubic yards of contaminated soil to prevent future exposure and future groundwater contamination. At Lava Cap Mine near Grass Valley and Nevada City, construction of a wetland-based water-treatment system was scheduled for late July. At Sulphur Bank Mine in Clearlake Oaks, a fall residential cleanup is planned at 13 properties, with about 6,000 cubic yards of waste to be removed and replaced with clean soil.
Groundwater treatment under Los Angeles
San Fernando Valley Area 1 addresses a contaminated drinking-water aquifer beneath the North Hollywood area of Los Angeles. EPA says it has been working with the city and state regulators to start two treatment plants, North Hollywood West and North Hollywood Central.
EPA’s July announcement says the systems are intended to provide up to 30,000 gallons per minute of drinking water, with startup activity listed for late July. That is a stated design or planned capacity, not confirmation that the plants are currently operating at full capacity. Treatment construction, operation and long-term monitoring remain separate steps.
Uranium waste on Navajo Nation lands
Northeast Church Rock is about 17 miles northeast of Gallup, New Mexico, in the Pinedale Chapter of the Navajo Nation. EPA says it is working with the Navajo Nation Environmental Protection Agency and New Mexico officials on cleanup overseen at the former uranium mine.
The July schedule calls for removing approximately 1 million cubic yards of uranium mine waste and moving it to a nearby engineered repository. EPA’s site page describes the larger cleanup in different terms, referring to approximately 1.4 million tons of contaminated soil to be consolidated at the nearby mill site. The July announcement’s cubic-yard figure and the site page’s tonnage are not interchangeable measurements.
The planned quantity is not newly removed material. EPA separately says earlier time-critical actions removed approximately 200,000 tons of contaminated soil from an adjacent residential area.
What happens next
The July 16 announcement is an agency schedule and implementation update. It does not establish that every listed project had begun by that date, and construction starts do not mean a site is fully remediated.
Depending on the site, later phases may include treatment, monitoring, capping, waste consolidation or additional excavation. For residents near the listed locations, the most useful next information will come from site-specific schedules and community notices describing when crews will enter properties, how material will be sampled and where contaminated waste will be taken.
The immediate significance is the move from planning toward physical cleanup at several long-running Superfund sites. Completion—and long-term protection of homes, drinking water and tribal lands—will require separate milestones.
Sources
- EPA construction schedule for Pacific Southwest Superfund sites
- EPA Argonaut Mine reports and documents
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