The more than 400 natural gas storage facilities across the country should phase out the flawed well designs like the one that produced the massive leak at Aliso Canyon last year, a federal report released on Tuesday said. That was among the 44 recommendations for reducing the risk of future calamities.

The Aliso Canyon leak, which emitted about 90,000 metric tons of methane into the air and forced thousands of residents to evacuate Los Angeles’ Porter Ranch community, was traced to a common and problematic “single-point-of-failure” well design.

The new report, published almost a year after the Aliso Canyon leak began, was written by an interagency task force created after the leak drew nationwide alarm and became the largest methane leak from a gas storage facility in the U.S. The task force includes experts from the Department of Energy, the Environmental Protection Agency, the Federal Energy Regulatory Commission and various national labs.

The report provides suggestions for improving storage well safety, emergency planning, mitigating greenhouse gases and addressing public health concerns. The report recommends that new facilities be built with double-barrier designs to help prevent leaks. Aging facilities like the 40-year-old Alison Canyon should be similarly retrofitted to contain leaks.

These sites are regulated by a patchwork of state and federal rules. Critics say they are inadequate, but the Aliso Canyon incident has prompted some regulatory reform. In June, Congress ordered the Pipeline and Hazardous Materials Safety Administration—the federal pipeline regulator—to issue minimum standards for all gas storage facilities within two years. An interim final rule is expected by the end of 2016. California has also passed new regulations.

Adam Peltz, an attorney for the Environmental Defense Fund’s oil and gas program, said the federal report is “a serious and well-thought-out effort to explore this issue from all the right angles. And in our first read, we agree with [and] appreciate a lot of the findings and recommendations.”

EDF, an environmental group headquartered in New York, was among the first to investigate the leak’s climate change impact. According to the report, various calculations from regulators, scientists and Southern California Gas Co., the company responsible for the leak, place the leak’s volume between 84,000 and 97,000 metric tons of methane.

Methane is a powerful greenhouse gas that’s much more potent than carbon dioxide, though methane’s global warming potential decreases over time.

Over a 100-year time period, 90,000 metric tons of methane are equivalent to the climate-forcing emissions of 500,000 cars driving on roads for a year, the report’s authors said.

Over 20 years, the potency increases, and the emissions would equal the effect of 2 million cars driving for a year. (For comparison, there were about 253 million vehicles on U.S. roads in 2014).

California has ordered Southern California Gas Company (SoCal Gas) to mitigate the climate impacts of the leak, but regulators and the company disagree on how to calculate the damage. The California Air Resources Board (CARB) decided to use the 20-year time frame, which gives the methane a global warming potential of 8 million metric tons of carbon dioxide, while SoCal Gas prefers a 100-year time period, which places the emissions at 2 million metric tons of carbon dioxide equivalent.

Stanley Young, CARB’s communications director, said the agency based its decision on the latest science. The 100-year cycle “is not meant to be an accounting of the environmental impact,” Young said in an email.

The 20-year time frame better represents the amount of warming caused by methane, and the recent international agreement on controlling highly potent greenhouse gases called HFCs, which are used in air conditioners, underscores the importance of addressing short-term impacts, he said.

Timothy O’Connor, director of EDF’s California oil and gas program, said EDF supports the agency’s decision.

More than a quarter of the warming the Earth experiences today comes from short-lived gases like methane, O’Connor said. “If we’re going to counteract and prevent the worst impacts of climate change, we need to be reducing them now.”

SoCal Gas declined to answer questions beyond the statement on its website, which says the company is reviewing the federal report. It also says SoCal has followed new state laws by installing new casings, or barriers, in its gas storage wells as additional protection against future leaks. Those are consistent with the federal report’s recommendations.

Peltz said the gas industry is concerned about the cost required to retrofit single-barrier wells, but “no one expects the changes to be made overnight. It could be quite a long time before [all the wells] in the United States are up to this standard.”

The report also recommends well integrity measures and risk reduction steps based on guidelines created by the American Petroleum Institute, an industry trade group.

Other recommendations involve public health concerns, including urging more research on the health effects of exposure to mercaptans and developing better air monitoring around the facilities. Soon after the Aliso Canyon leak began, many Porter Ranch residents reported nausea, headaches, nosebleeds and skin rashes, likely triggered by mercaptans, a type of odorant added to the natural gas to help signal leaks. Although health officials said the mercaptans would not cause long-term impacts, there is virtually no research on prolonged exposure, and air monitors did not track all the chemicals present in the gas.