By Rory Carroll
SAN FRANCISCO (Reuters) - California on Friday said it would review wells where oil drilling waste water from the process known as hydraulic fracturing, or fracking, is disposed to ensure they are not contaminating drinking water.
The move comes after the state ordered oil companies to shut down 11 wells on July 1 in Kern County, an area in the state’s Central Valley that is home to the bulk of its crude oil production. Like the rest of the state, Kern County is being ravaged by a severe drought that has led to mandatory water restrictions.
"We shut these wells down and ordered the operators to provide information and conduct testing to ensure human and environmental health and safety are not at risk," said Steve Bohlen, the state’s oil and gas supervisor and head of the state’s Division of Oil, Gas and Geothermal Resources.
The agency said there is no direct evidence that any drinking water has been affected and said the stop orders were issued out of "an abundance of caution."
The companies operating the 11 wells are Longbow, Macpherson Operating Co, Race Diversified Corp, R&R Resources, Redbank Oil Co, SOC Resources Inc and CMO Inc.
Since the initial orders were issued, two of the wells have been authorized to resume operations, the agency said on Friday. California has 1,500 waste water injection wells, the state agency said.
The state's review of existing wells and the injection well approval process is being carried out in conjunction with the U.S. Environmental Protection Agency and is expected to take 12 to 18 months to complete.
(Reporting by Rory Carroll; Editing by Lisa Shumaker)