PORTLAND (AP) — Investigators say many Oregon retailers continue to sell water in plastic bottles that have not been marked for deposit despite a law passed by the last Legislature that they be worth a nickel each.

It was the first significant expansion of Oregon’s bottle bill since the state became the first in the nation to put one in effect in 1971.

The sale of unmarked bottles means customers may pay their nickel deposit, but since scanners couldn’t register them, deposit requests could be refused.

The Oregon Liquor Control Commission sent staffers to check on stores after the law became effective Jan. 1 and they found unmarked bottles at many stores, spokeswoman Christie Scott said.

The OLCC also received consumer complaints of smaller retailers refusing to redeem deposits on unmarked bottles, Scott said.

The law does not require retailers to redeem them. However, manufacturers must properly label bottles and stores must clear their shelves of unmarked bottles.

The OLCC, which enforces the bottle bill, could file misdemeanor charges or suspend liquor licenses for violations.

Inspectors will begin issuing violation notices Monday, Scott said.

Criminal charges are rare, but because there are so many companies not complying, there could be some criminal citations, she said.

Scott said the commission notified retailers and manufacturers of the change in June and allowed them to start labeling water bottles with the nickel deposit starting July 1.

Oregon adopted the original bottle bill in 1971 as a litter-control measure, becoming the first state to require deposits on soft drink and beer containers. The 2007 Legislature added water and flavored-water bottles effective this Jan. 1.

Empty water bottles are seen as a major solid waste disposal problem.

It’s unclear if stores are working through old inventory or if some manufacturers have yet to label their bottles to comply with Oregon law.

If manufacturers are labeling new bottles correctly, the problem would work itself out quickly at high-volume stores. It could linger at stores with slower sales.

Scott said the number of unmarked bottles varied by store with no clear pattern.

On Wednesday, most major water brands were marked at the Safeway and Fred Meyer stores downtown. Both had some unmarked bottles.

John Andersen, president of the Oregon Beverage Recycling Cooperative, said grocers tried hard to get unmarked bottles off their shelves before Jan. 1.

His group, which handles most of Oregon’s bottle bill returns, told more than 3,500 store owners that they should refund deposits on unmarked bottles for the foreseeable future.

The cooperative’s bottle return machines are programmed to give nickels back for marked and unmarked water bottles, Andersen said.

And most grocers and other chains have issued directives notifying employees that they should accept unmarked bottles if they hand-count them, he said.

But compliance can vary.

“If the bottle collection kid at the store didn’t get the directive, the only thing he may know is, ‘I’m supposed to look for the 5 cents marking,’ “Andersen said.

“The reality for the public is the stuff should be accepted.”