AB 1031 removes specified geothermal and mining-related waste streams from broad coverage under California's Hazardous Waste Control Law and redirects some disposal oversight to the State's regional water boards and to federal regulatory standards. The bill draws a line between drilling-related geothermal waste (explicitly exempted because regional water boards regulate disposal) and other geothermal wastes, and it creates a narrow, conditional state exemption for wastes from ore and mineral extraction and processing.
The measure is surgical: it exempts some wastes from the chapter while preserving targeted state requirements where a waste would otherwise meet California's hazardous-waste definition or fail federal exclusions. For industry that meets the specified conditions—closed piping transfers, compliance with 40 CFR standards, and exclusion of solid/semisolid residuals—the bill reduces overlap with state hazardous-waste rules.
But it also leaves open several practical questions about definitions, oversight, and who actually enforces remaining obligations.
At a Glance
What It Does
The bill exempts geothermal drilling waste from the Hazardous Waste Control Law on the grounds that regional water quality control boards regulate disposal. It also exempts certain mining and mineral-processing wastes from the chapter, but subjects them to Article 9.5 and to Part 2 of Division 45 when those wastes would otherwise be classified as hazardous under California law. The text conditions an exemption for spent geothermal brine on closed-piping transfer, return after processing, compliance with specified federal standards, and the absence of solid/semisolid hazardous residuals.
Who It Affects
Geothermal developers and operators, companies that recover minerals from spent geothermal brines, mining and mineral processing operations, regional water quality control boards, and state hazardous-waste regulators (including agencies administering Article 9.5 and Division 45). Facilities that manage filter cakes, used oil, or other solid residuals are specifically implicated by the carve-outs and exceptions.
Why It Matters
The bill narrows the scope of California's hazardous-waste statute for particular energy- and resource-related waste streams, potentially reducing duplicative permits and compliance costs while shifting regulatory responsibility and creating conditional, federally referenced compliance gates. That shift matters for permitting, monitoring, and enforcement strategies for both operators and regulators.
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What This Bill Actually Does
AB 1031 reorganizes who regulates certain geothermal and mineral‑processing wastes and under what conditions the state hazardous‑waste statute continues to apply. It begins by saying geothermal waste that is generated by drilling for geothermal resources falls outside the Hazardous Waste Control Law because disposal of that waste is already regulated by the state’s Regional Water Quality Control Boards.
That is a jurisdictional reallocation: the bill does not create new state hazardous‑waste duties for drilling wastes, instead pointing operators and regulators toward water‑board authorities for disposal oversight.
The bill then creates a broader exemption for wastes produced by the extraction, beneficiation, and processing of ores and minerals when those wastes are not already subject to regulation under the federal Resource Conservation and Recovery Act (the "federal act"). But the exemption is conditional.
If a waste would otherwise meet California’s hazardous‑waste definition (as referenced to Section 25117 and implementing regulations), the bill preserves certain state requirements by keeping those wastes subject to Article 9.5 and to Part 2 of Division 45. In short, California withdraws some chapter coverage but keeps targeted state controls for wastes that meet the state hazardous‑waste tests.The bill spells out what counts as mining/mineral wastes and sets specific conditions for a common geothermal stream: spent brine that is moved through a closed piping system to an adjacent facility for reclamation or mineral recovery.
To qualify for the exemption the spent brine (and any liquid residuals) must be managed in accordance with the federal standards the bill cites, be returned via closed piping after processing, and must not be a solid or semisolid hazardous residual (the text explicitly calls out materials such as filter cakes as falling outside that liquid‑residual treatment).Finally, AB 1031 exempts geothermal wastes generated during exploration, development, or production that do not result from drilling, but it leaves explicit exceptions for hazardous wastes that are not directly tied to geothermal operations or that the federal rule does not exempt—used oil from vehicles is given as an example. Those carve-outs create a layered regime: some geothermal and mineral-processing wastes leave the chapter entirely, some remain subject to narrow state rules, and some stay fully subject to hazardous‑waste regulation depending on source, form, and federal‑rule status.
The Five Things You Need to Know
Section (a) exempts geothermal waste created by drilling for geothermal resources from the Hazardous Waste Control Law, citing regulation by the Regional Water Quality Control Boards as the basis.
Subdivision (b) exempts wastes from extraction, beneficiation, and mineral processing that are not regulated under the federal act, but keeps them subject to Article 9.5 and Part 2 of Division 45 if they would otherwise be classified as hazardous under Section 25117 and related regulations.
The bill defines eligible 'spent brine solutions' as those transferred via closed piping to an adjacent reclamation or processing facility, managed in accordance with 40 CFR 261.4(a)(17)(i)-(iii), returned via closed piping, and not a solid or semisolid hazardous residual.
Paragraph (c)(1) exempts geothermal waste (other than filter cake) generated during exploration, development, or production that does not result from drilling, carving out a specific residual form from the exemption.
Subdivision (c)(2) preserves the state regulatory status for hazardous wastes that are unrelated to geothermal operations or are not covered by federal exclusions—used oil is cited as a non‑exempt example.
Section-by-Section Breakdown
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Exemption for drilling‑related geothermal waste; shifts disposal oversight to regional water boards
This provision removes geothermal waste produced by drilling for geothermal resources from the chapter entirely, anchoring the change on the assertion that regional water boards regulate disposal. Practically, operators who generate drilling wastes will look to water‑board permits and discharge/groundwater controls rather than DTSC hazardous‑waste permits. The statutory text does not itself create a new permitting mechanism; it reallocates regulatory responsibility and may require coordination between water boards and hazardous‑waste regulators to prevent gaps.
Conditional exemption for extraction/processing wastes, with state safeguards for wastes that meet California's hazardous definition
The bill excludes from the chapter wastes from ore and mineral extraction/processing that are not covered by the federal act, but it explicitly preserves Article 9.5 and Part 2 of Division 45 for cases where those wastes would meet California's hazardous‑waste criteria. That means the exemption is not blanket: operators and regulators must apply California's hazardous‑waste tests (Section 25117 and implementing regs) to determine whether limited state controls remain in effect. For compliance teams, the immediate implication is a two‑step inquiry—determine federal coverage first, then apply California's hazardous‑waste definitions to decide whether Article 9.5/Part 2 duties survive.
What counts as mining/mineral wastes and the narrow 'spent brine' pathway
The bill enumerates three categories of mining/mineral waste—excavated natural materials, residuals after processing, and certain spent geothermal brines sent via closed piping for recovery. For the spent‑brine pathway the exemption requires compliance with specific federal standards (40 CFR 261.4(a)(17)(i)–(iii)), closed‑loop transfer to an adjacent facility, return via closed piping, and an absence of solid/semisolid hazardous residuals (explicitly excluding filter cake). Those conditions impose engineering and operational requirements—closed piping and return flow—plus a documentation trail showing alignment with the cited federal standards.
Exemption for non‑drilling geothermal waste generated during exploration, development, or production
This clause exempts geothermal waste (other than filter cake) generated during exploration, development, or production when that waste is not a result of drilling. It creates a categorical carve‑out for liquid geothermal residues tied to normal production activities, which can lower compliance obligations for active geothermal plants—but only when the waste fits the specified non‑drilling profile and is not a disallowed residual form.
Explicit exceptions—hazardous wastes unrelated to geothermal operations and federal non‑exempt wastes remain regulated
The bill makes clear that the exemptions do not swallow all wastes connected to geothermal operations: hazardous wastes that are not directly associated with geothermal activity or that federal rules do not exempt remain subject to the Hazardous Waste Control Law. The text gives used oil as an example. This carve‑out forces site‑by‑site analysis of waste streams and means operators cannot assume a blanket exemption for every operational waste.
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Explore Environment in Codify Search →Who Benefits and Who Bears the Cost
Every bill creates winners and losers. Here's who stands to gain and who bears the cost.
Who Benefits
- Geothermal developers and operators — they gain narrower state hazardous‑waste liability for drilling‑related wastes and for certain production liquids, reducing duplicative compliance and potentially lowering permit and management costs when wastes meet the exemption conditions.
- Mineral recovery and adjacent reclamation facilities — facilities that receive spent brine via closed piping for beneficiation can operate under a clearer exemption pathway if they meet the federal‑standards and return‑flow conditions, simplifying the regulatory calculus for integrated operations.
- Companies processing ore and mineral residuals — when their wastes are not covered by the federal act and do not meet California's hazardous definition they avoid chapter obligations, which can reduce manifesting, storage, and permitting burdens.
Who Bears the Cost
- Regional Water Quality Control Boards and local regulators — the bill places more disposal‑related oversight emphasis on water boards for some drilling wastes, increasing their workload for monitoring, permitting, and enforcement without providing new statutory program resources.
- California hazardous‑waste regulators (e.g., DTSC administrators of Article 9.5 and Division 45 functions) — although not directly bearing compliance costs for exempted streams, they inherit a more complex gatekeeping role to identify when exemptions do not apply and to enforce residual state obligations.
- Facilities that handle solid/semisolid residuals (filter cakes) and used‑oil handlers — these waste forms fall outside the liquid‑residual exemptions and therefore retain full hazardous‑waste obligations, potentially increasing cost and operational complexity compared with liquid streams that qualify for the carve‑outs.
Key Issues
The Core Tension
AB 1031 pits regulatory efficiency and reduced duplicative oversight against environmental‑protection and enforcement certainty: it lowers state hazardous‑waste obligations for specific energy and mineral wastes to streamline operations, but doing so narrows the statutory safety net and relies on precise, often technical tests and cross‑agency coordination to prevent oversight gaps.
The bill’s operational clarity depends on several narrowly worded terms that the text does not fully define: 'regulated by the California regional water quality control boards,' 'adjacent facility,' and what counts as a 'solid or semisolid hazardous residual' (the example of filter cake highlights the line‑drawing problem). Those gaps create implementation questions—who makes the initial jurisdictional determination, what documentation suffices to prove closed‑piping transfer and return, and how regulators will coordinate enforcement when a stream crosses the exemption boundary.
The bill also leans on federal standards (40 CFR 261.4(a)(17)(i)–(iii)) as a gate for state exemptions. That creates a dependency: operators must track federal regulatory changes to preserve state exemptions, and California agencies must build processes to verify federal‑standard compliance.
Finally, shifting some disposal oversight to regional water boards reduces duplicative state permitting but risks uneven enforcement across basins and may require significant new monitoring capacity at the water‑board level—an unfunded administrative consequence the statute does not address explicitly.
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