The California Air Resources Board's Mine Methane Capture Compliance Offset Protocol was adopted on April 25, 2014. In the twelve years since, it has never been amended. Not once. During that time, it has authorized over $680 million in carbon credit value from companies extracting methane from abandoned coal mines across Appalachia.
The protocol is technically rigorous about one thing: measuring gas. It specifies methane detection methods, destruction efficiency thresholds, monitoring frequencies, and quantification formulas calibrated to several decimal places. When it comes to counting molecules of methane, this document is meticulous.
When it comes to water, it is silent.
What the Protocol Bans
Section 2.4(i)(2) of the protocol contains a prohibition on "fluid/gas enhancement" — specifically, operators cannot inject fluids or gases into mine workings to push methane toward collection points. This makes intuitive sense: if you're claiming credit for destroying methane that would have vented anyway, you shouldn't be artificially enhancing the flow.
This is the protocol's sole acknowledgment that human manipulation of underground conditions could affect methane availability. It addresses one direction of the problem: pushing methane out by pushing something else in.
What It Ignores
The protocol is entirely silent on the other direction: removing water to keep methane flowing.
When a coal mine is abandoned, pumps are turned off. Groundwater gradually fills the workings. As water rises, it seals off methane pathways. Eventually, if left alone, many mines flood completely — trapping methane in coal seams where it stays indefinitely. No venting. No emissions. No problem.
But you can't sell carbon credits for methane that isn't venting. A flooded mine produces no credits.
The protocol defines a "flooded mine" (Section 1.2(a)(15)) as one "filled with water as a result of pumps being turned off at abandonment and with no detectable freely venting methane." It explicitly carves out mines that "pump water due to regulatory or legal requirements" as not flooded — regardless of how much water is being managed.
So: if an operator pumps water out of an abandoned mine — keeping water levels low enough that methane continues to vent — and that methane is then captured and destroyed — the credits are valid. The protocol doesn't ask why the mine isn't flooded. It doesn't ask where the pumped water goes. It doesn't ask whether the dewatering is creating acid mine drainage downstream.
The Baseline Problem
The protocol uses a "hyperbolic decline curve" to establish baseline emissions — how much methane a mine would vent without intervention. This curve is calibrated using historical data from MSHA (Mine Safety and Health Administration), typically from periods when mines were actively managed: ventilated, drained, and maintained.
But that historical data reflects managed conditions. An actively pumped mine vents more methane than one allowed to naturally flood. By using managed-era data as the baseline, the protocol may systematically overestimate what emissions would be without the project — because without the project (and without pumping), many mines would flood and stop emitting.
The implication: operators may be generating credits for destroying emissions that exist only because of their own water management activities. They're not preventing emissions that would happen anyway. They're maintaining conditions that allow emissions to continue — then getting paid to clean up what they enabled.
What Verifiers Don't Check
Third-party verification bodies — SES, Inc., Ruby Canyon/TÜV SÜD, SCS Global Services — audit these projects against the protocol's requirements. Their scope includes:
- Was methane captured? How much?
- Was it destroyed efficiently?
- Were measurements accurate?
- Were instruments calibrated?
Their scope does not include:
- Is the operator pumping water to maintain methane flow?
- Where does pumped water discharge?
- Are downstream waterways being contaminated?
- Have nearby wells been affected?
- Are communities experiencing health impacts?
This isn't verifier negligence. The protocol doesn't ask these questions, so verifiers don't answer them. The scope of audit is the scope of the protocol. Nothing more.
Comparison to Other Standards
CARB's approach is an outlier among major carbon credit programs:
UN Clean Development Mechanism (CDM): Requires environmental impact assessments and stakeholder consultation for all projects.
Verra Verified Carbon Standard (VCS): Requires projects to assess and address negative environmental and social impacts. Stakeholder consultation mandatory.
American Carbon Registry (ACR): Requires consideration of environmental co-impacts in project documentation.
CARB Mine Methane Capture: None of the above. No environmental assessment. No stakeholder consultation. No community notification. No water monitoring.
Among all major offset standards globally, CARB's MMC protocol appears to be the least protective of communities affected by project activities.
Twelve Years, Zero Amendments
The protocol has not been updated since its adoption in 2014. A 2016 FAQ document provided operational clarifications but made no substantive changes to environmental safeguards (because there were none to change).
In those twelve years:
- Credits issued have grown from hundreds of thousands to millions per year
- 2025 set a record: 5.9 million credits issued
- Market value has ranged from $24 to $42 per credit
- Not a single water quality monitoring requirement has been added
- Not a single community notification requirement has been added
- Not a single amendment has been proposed publicly
What Would Fix This
The fix isn't complicated. It doesn't require killing the program:
- Baseline water quality testing before project commencement
- Ongoing downstream monitoring at defined points throughout operation
- Dewatering disclosure — if you're pumping water, report it: how much, where it goes, what's in it
- Community notification when new projects commence in a watershed
- Credit suspension authority if environmental harm is documented, pending remediation
These additions would cost operators a fraction of their credit revenue. They would not make projects uneconomic. They would simply make the program honest — ensuring that climate benefits in California don't come at the cost of poisoned water in Appalachia.
A system that measures every molecule of gas but ignores every drop of water isn't an environmental program. It's an accounting exercise. And accounting exercises don't protect people.