made the comment in a letter to the Texas Railroad Commission,
which regulates the oil industry in the top crude-producing
Quakes have been tied to the injection of saltwater, a normal
byproduct of oil and gas drilling, into deep disposal wells and
The Railroad Commission, which was not immediately available for
comment, has in the past questioned the causal link found in
university studies. But Texas has moved to install more
earthquake monitoring stations.
"EPA believes there is a significant possibility that North
Texas earthquake activity is associated with disposal wells,"
said the Aug. 15 letter reported by the Texas Tribune on
The EPA said it was concerned about seismic activity in the
Dallas-Fort Worth area because of its potential to affect
underground sources of drinking water.
Regulators in Oklahoma have ordered dozens of disposal wells to
be shut in to curb a spate of quakes in that state.
The use of disposal wells intensified during the fracking boom,
although U.S. oil and gas drilling has slowed recently on the
worst price crash in years.
(Reporting by Terry Wade; Editing by Peter Cooney)
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