JUNEAU, Alaska — Princess Cruise Lines has agreed to pay $20,000 for alleged discharge of pool water in Glacier Bay National Park and Preserve.

The U.S. Environmental Protection Agency announced the penalty. It said the case was settled in December.

The case dates to May 2011. According to the consent decree, a software malfunction on the Golden Princess ship caused its pool dump valves to open. The incident resulted in about 277 tons of pool water being discharged. A vessel general permit, under which the ship was operating, prohibited discharge of pool or spa water in the park.

EPA said Princess notified the agency of the discharges the day after they happened.

A Princess spokeswoman says the company sincerely regrets the incident and took measures to prevent it from happening again.