There's a twist in the big gas-leak settlement announced in California this week: It includes a program to pay for methane gas collection at a dozen of the state's dairy farms.

State and local officials reached a $119.5 million settlement with the Southern California Gas Company on Wednesday to mitigate climate impacts and address ongoing health concerns from one of the largest natural gas leaks in U.S. history.

The dairy part of the settlement would address a substantial source of methane, a potent greenhouse gas that contributes to climate change. State officials say the plan would reduce by at least 109,000 metric tons the amount of methane that would otherwise be released into the atmosphere over a 10-year period.

That's the same amount that was released over several months following a blowout in October 2015 at the Aliso Canyon gas storage facility on the outskirts of Los Angeles.

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The settlement, which is subject to approval by the Los Angeles Superior Court, would ensure that methane is collected at 12 or more dairies and fed into the state's existing natural gas pipeline and storage network and then used as transportation fuel, according to a California Air Resources Board document about the settlement. It would also fund a long-term study to assess health impacts from the Aliso Canyon gas leak in nearby communities and would provide funding for ongoing air quality monitoring of emissions there.

"This leak undermined our crucial work to reduce greenhouse gas emissions and protect our people and the environment," California Attorney General Xavier Becerra said in a statement. "If approved, this settlement will go a long way in addressing the short and long-term harms attributable to the leak."

Could the Solution Lead to More Leaks?

Environmental advocates had mixed reactions to the plan.

"Making the atmosphere whole, reducing as much pollution as what was put out is great progress and a great step forward," said Timothy O'Connor, who directs the Environmental Defense Fund's oil and gas program in the state.

O'Connor stressed, however, that the projects must be done correctly.

"So far, we've seen in California investment in biogas facilities where those facilities have been allowed to leak, and that is a problem," he said. "If we are going to build 12 facilities to capture methane in California, they need to be held to the highest standard for leak abatement so we don't spend a bunch of money and wind up in the same place."

Methane is a short-lived climate pollutant—a potent one that makes even small leaks significant contributors to global warming. The proposed digesters would capture methane emitted from liquid manure storage lagoons. If they captured 109,000 metric tons over 10 years, that would be about 2.6 percent of the state's methane emissions from manure over that period, based on an analysis by O'Connor of 2016 data from the California Air Resources Board.

Another major source of methane emissions is the existing pipeline infrastructure that any new biogas project would feed into, O'Connor said.

"The pipes in California, the distribution and transmission system, leak as much every year as Aliso Canyon put out," he said. "It's a very strong reminder that the Public Utilities Commission and the Air Resources Board need to stay focused on keeping utilities' feet to the fire to manage their methane."

State Law Requires Dairies to Reduce Methane

Brent Newell, an attorney previously with the Center on Race, Poverty & the Environment, said the mitigation feature is little more than a handout to the dairy industry to meet existing environmental requirements.

A draft of the current mitigation plan was developed in March 2016. In September of that year, California passed a law requiring dairies to reduce methane emissions from manure by up to 40 percent.

"This agreement is providing subsidies to the reduction of methane at dairies that dairies would otherwise have to do," Newell said.

The requirements on dairies put in place by the 2016 law doesn't come into effect until 2024 at the earliest, and the current mitigation plan provides loans, not grants, said California Air Resources Board spokesman, Stanley Young.

"This accelerates the ability of dairies to reduce methane emissions from their lagoons sooner," Young said.

There will now be a 35-day public comment period on the mitigation agreement before the court makes a decision on how to proceed.