LAKE WHITNEY (September 28, 2011) --- Looters are taking advantage of dropping area lake levels to find long hidden artifacts are that’s creating big problems for authorities.

Since Lake Whitney's water level dropped, five sites full of Native American artifacts are now accessible for the first time in decades.

Some of these sites date back more than 8,000 years.

State and federal law protect the artifacts.

It’s against federal law to remove any Native American artifact from government property and in Texas, doing that also violates the state Antiquities Code.

But in the past few months, authorities say more than thirty people have been caught digging illegally.

Authorities say the looters could also be disturbing ancient burial grounds.

"A lot of Native American tribes and cultures buried their family members and loved ones where they lived so it’s all intertwined," said Brady Dempsey, of the U.S. Army Corps of Engineers.

Once the damage has been done to these sites, the effects are nearly impossible to reverse, Dempsey said.

In one area, he said, looters broke concrete open, burrowed in under it and then sifted through the dirt, taking what they could and leaving the arrest behind.

“They've just scrambled the archeological record," Dempsey said.

The damage looters leave behind is becoming increasingly expensive.

Recently a dig site had to be repaired at Lake Whitney at a cost of more than $30,000.