When the Colorado Oil and Gas Conservation Commission ordered NGL Water Solutions to stop fracking wastewater injection operations a month ago, a team of University of Colorado Boulder researchers began conducting its own investigation.

NGL, formerly known as High Sierra Water Services, was given permission to resume its activities at a 10,800-foot-deep well a few weeks later, but the CU findings suggest that shouldn’t have happened. Anne Sheehan and her team found that the well is linked to more than 200 earthquakes, the geophysics professor in the CU Department of Geological Sciences told Boulder County Business Report.

She said the group found “quite a few” earthquakes with epicenters within two miles of the well.

Two earthquakes—with magnitudes of 3.4 and 2.6—took place within mere miles of the well. Shemin Ge and Matthew Weingarten, also of CU, also found that activity within fracking wastewater injection wells likely caused earthquakes in central Oklahoma.

NGL operates 11 of the 29 fracking wastewater injection wells in Weld County, CO. When the Colorado Oil and Gas Conservation Commission allowed NGL to resume activities, it began injecting 7,500 barrels per day at maximum pressure.

“We’ll continue to closely monitor and accumulate all available information at this location,” Colorado Department of Natural Resources spokesman Todd Hartman told the Report, “and work with partners to continue understanding how best to limit and prevent potential seismic impacts related to deep injection generally.”