<p>The state's cruise ship program manager says two Royal Caribbean Cruises Ltd. ships violated visible air emissions standards last year. </p><p>The ships were the Vision of the Seas and the Serenade of the Seas, on July 1 and Aug. 9 last year. </p><p>Royal Caribbean did not respond Friday afternoon to requests for comment. </p><p>Cruise ship program manager Denise Koch of the Department of Environmental Conservation notified Royal Caribbean of the violations on Monday. </p><p>Enforcement isn't over, as the state Department of Law takes the case from here. The cruise line can still argue that DEC was wrong. </p><p>Royal Caribbean may be liable for criminal or civil penalties. Past enforcement cases have cost cruise lines $27,500 per violation. The Department of Law also could suspend penalties contingent on future good behavior, or waive them entirely. </p><p>The state's air quality standards come from the U.S. Environmental Protection Agency. They are designed to keep people from breathing harmful sulfur and nitrogen compounds and particulate matter. </p><p>Plumes are tested not with gadgets that measure those harmful compounds, but by how thick they look to the human eye. EPA-trained observers are certified to reliably assess the opacity of a smokestack. </p><p>Cruise ships' plumes are not allowed to be more than 20 percent opaque for more than three minutes in any hour, except when they're casting off or coming into port. </p><p>In Southeast, weather can make it difficult to take readings. EPA guidelines require no-rain conditions. </p><p>Last year, 30 cruise ships visited Alaska. DEC did more than 170 readings. </p><p>Ships can and do report their own violations to the department, Koch said. They did not in either of these incidents, though. </p><p>Public complaints also play a role. They don't trigger a violation, but the department generally follows up on complaints with readings. Koch said there is some correlation between the number of notices of violation and the number of public complaints. </p><p>&quot;I find some of the complaints are when the plumes combine a bit and form what we sometimes call a haze,&quot; said Ed White, of the cruise ship program. </p><p>This year, the department heard more complaints from Ketchikan and Skagway as well as Juneau, White said. </p><p>The state found the most violations in the first two years of the cruise ship regulatory program. Fifteen ships were cited for violations in 2000, and 11 in 2001. Since then, violations have dropped off to one or two a year, save 2006, when there were none. </p><p>The two Royal Caribbean ships are the only air quality violators being cited for last year's cruise ship season. </p><p>These cases are coming out late. Ordinarily, the cruise ship program handles enforcement cases in the fall after the cruise ship season. But in the last year the department has been busy implementing several new programs, such as for the general wastewater discharge permit, Koch said. </p><p>Enforcement ramped up a bit this year, as the department had three people instead of one certified to take readings. The 2008 enforcement cases are expected by the end of the month. </p>