California energy officials said on Wednesday that they have ordered 475 underground injection control (UIC) wells shut down by Feb. 15.

Operators using the targeted wells could face fines of up to $25,000 per day if they fail to shut them down, but industry groups in the state point out that there is no evidence that drinking water supplies were contaminated by the wells in question.

California water and oilfield regulators provided an update on the state's review of UIC wells and their potential effect on drinking water aquifers, which was kicked off nearly three years ago and led to the identification of more than 5,600 class II wells that had been permitted for injection into potentially nonexempt aquifers.

"We believe that this approach will bring the state into compliance [with federal requirements] and protect public health and the environment, while avoiding unnecessarily disrupting oil/gas production in instances where the state has already done an evaluation of a proposal and believes the aquifer exemption as submitted by the state will receive [federal] approval," said Ken Harris, state oil/gas supervisor and head of the Division of Oil, Gas and Geothermal Resources (DOGGR), and Jonathan Bishop, chief deputy director of the California Water Resources Control Board.

In their submittal to the regional U.S. Environmental Protection Agency (EPA) office, the two state officials said that if EPA ultimately rejects the state's proposed exemptions, their agencies would take "immediate action" to halt UICs in the affected wells.

Rock Zierman, CEO of the California Independent Petroleum Association, said "there are still several duly permitted operations that will be shut down through no fault of their own, but rather because of delays by regulators." He expressed appreciation for state efforts cutting delays.

“We appreciate the state taking steps to ensure that paperwork delays do not create the unintended consequence of threatening the majority of California’s energy supply, especially given there is no evidence of environmental harm from this permitted production, which has occurred safely for more than 30 years," Zierman said.

Two years ago the state came under fire from federal reviews that found regulators allowed oil companies to contaminate protected aquifers, prompting DOGGR and the water agency officials to file a plan with EPA to correct regulatory deficiencies. The focus of concern was squarely on injection wells, which have been part of the state's oil/gas landscape for decades.

Last fall, a California Superior Court judge in Alameda County upheld the state's ongoing program for dealing with the UIC wells. Judge George Hernandez found that DOGGR did not violate its EPA agreements that allow the state to administer UIC programs to protect drinking water aquifers.

California's initial review in 2014-2015 of more than 50,000 class II injection wells involving 75 oilfields identified up to 5,625 wells that had been permitted for injection into potentially nonexempt underground drinking water sources. Then, DOGGR and state water authorities worked collaboratively to pare down the numbers. "This initial review employed a conservative screening criteria, and it is now clear that it captured wells that are not improperly injecting," the agencies told EPA in their letter last Tuesday.

DOGGR said the state will be enforcing the Feb. 15 deadline on wells in 23 oilfields, and will be allowing injection to continue in aquifers in 29 other fields covering 1,650 wells, pending federal EPA approval. If operators inject into nonexempt aquifers in any other fields after Feb. 15, they will be fined up to the $25,000 daily maximum, state officials said.