The state fined 30 oil companies on Thursday for failing to meet a deadline to report information about the source, volume and disposal of water used in oil and gas production.
Under a 2014 law, California's 433 oil producers were required to report the data to the California Department of Conservation, but only half filed completed reports in time. Another quarter of the companies complied but turned in incomplete reports.
The 30 companies, which the state said made no apparent attempt to file reports, were given the maximum civil fine of $4,500. Operators who fail to meet subsequent reporting deadlines after being fined may be subject to larger civil penalties, said Steve Bohlen, the state oil and gas supervisor.