MEDFORD (AP) — An Oregon man who searches for old bottles hit the national spotlight with an appearance on a the Travel Channel show “Cash and Treasures.”

But Dale Mlasko could have done without the publicity.

The Oregon State Preservation Office sent a letter alerting Mlasko that it is illegal for anyone to intentionally unearth artifacts more than 75 years old without a permit from the state — even on private property.

Unearthing such items also must be witnessed by an archaeologist.

“I did not know this law was in effect,” Mlasko said. “I don’t even keep most of the stuff. I give it to the property owner.”

Mlasko, 44, of Medford has been following his passion for hunting glass since he was a boy. He searches for bottles from the 1800s and early 1900s on private property in Northern California and Southern Oregon. He asks the owners for permission.

Susan Lynn White, Oregon assistant state archaeologist, said she doesn’t think Mlasko meant any harm, and the state doesn’t want to appear punitive or arbitrary — or even prohibit Mlasko from digging.

“We’re more interested in education, rather than punishment,” she said.

White said property owners shouldn’t worry about violating the law if artifacts are unearthed while digging up an old septic tank or installing a fence. Inadvertent discovery of historic matter is not illegal.

The digging, however, should cease until the state’s preservation office is notified and can assess the situation.

“Everything is context,” she said.

State officials were not the only ones to give Mlasko grief about his episode. He was blasted on an Internet-based forum, and Mlasko said he received “anonymous threatening letters from so-called archaeologists.”

Larry Smith, executive director of the Jacksonville Woodlands Association, wasn’t vitriolic, but he, too, supports the law.

“People need to be sensitive,” he said. “Once you move a bottle, once you move an arrowhead, the historical significance is reduced.”

Mlasko said he will comply with the Oregon law, but plans to dig more often in less-restrictive California. He thinks the Oregon law will have a chilling effect on his fellow hobbyists.

“A lot of bottle collectors have gone underground,” Mlasko said.