WELD COUNTY, Colo. -- Weld County is better known for cattle, agriculture and fracking, not earthquakes.
But two earthquakes in less than a month forced the state to shut down a drilling site for 20 days.
The closure will give experts time to figure out if an injection site drilled by High Sierra Water is the cause of the tremors.
The company injects waste water from fracking and other oil and gas use deep into the ground.
But now, the state wonders if that practice is a problem since both quakes originated from the same area.
In this quiet county, you can hear the birds chirp, watch the grass grow and lately, feel the ground shake.
“It did startle me,” Greeley resident Billy Nevill says. “I felt the shock wave come through the building.”
On May 31, a 3.4 quake roused Nevill from bed.
“I felt the concussions, I really didn’t feel the earth shake. Just heard a big boom,” Greeley resident Eric Angus says.
He jumped from his couch.
And now the state is jumping in to find out what caused that earthquake and another one on Monday that measured 2.6 magnitude.
"With those events, we made a decision to have the nearest injection well stop injecting so we can continue to gather data and study it,"Matt Lepore with the Colorado Oil and Gas Conservation Commission says.
At issue is a site east of the Greeley-Weld County Airport.
It’s the epicenter of the quakes and is also where High Sierra Water buries waste water fluid from fracking and other oil and gas uses.
The state wonders if there’s a connection between this activity and the earthquakes.
"We have not concluded there is such a link," Lepore says. "Also, we have not ruled out that possibility."
University of Colorado seismologists will monitor what earthquake activity there is when the company isn’t injecting waste water.
“I’m not real, real concerned. I’m a strong advocate of fracking and drilling," Angus says. "It’s done wonders for Colorado and I’d like to see it continue. So, I hope it’s not related."
Those who live near the drilling site say the earthquakes don’t have them shaking in their shoes.
Some ponder whether it’s the cost of oil independence.
“Nothing's for free," Nevill says.
During the 20-day halt, the state will also analyze seismic records at the High Sierra site to see if tremors were happening there even before they began injecting waste water in April 2013.
Harris Sierra Water did not return repeated calls and emails for comment.