Producers burned off, or flared, 0.154 bcfd of gas in August, up from 0.141 bcfd in July, the commission said in a report, boosting the percentage of gas flared to 5%.
The highest monthly percentage of gas flared was 36% in September 2011.
One billion cubic feet of gas is enough to supply about 5 million U.S. homes for a day.
The commission has set a goal of capturing at least 91% of gas pulled out of the ground after Nov. 1, 2020.
The number of producing wells, both oil and gas, rose to a preliminary record high of 18,380 in August from the prior all-time high of 18,185 in July.
