More than 230 cruise ships operate worldwide, often in pristine coastal waters. Many cruise lines offer excursions to private islands where snorkeling to admire the coral reefs and marine life is one of the options.

Yet the deep blue seas the ships navigate are being affected by vessels that travel back and forth on the same routes.

The downside of the fun, food and entertainment is the enormous amount of sewage, food and garbage, waste water from sinks, showers, laundries and kitchens and other wastes being discharged into the seas.

The wastes from the “floating cities” pose a threat to fragile ecosystems, to sea life, and even to people enjoying a day at the beach, say the U.S. Environmental Protection Agency and groups such as Bluewater Network, a coalition of 53 environmental organizations.

A cruise ship with 3,000 passengers can generate 210,000 gallons of waste and sewage and 1 million gallons of gray water from showers and drains in a typical week, the EPA says. There are also discharges of bilge water which may contain oil, grease and other contaminants.

The nation’s top three cruise ship departure ports are in Miami, Fort Lauderdale and Cape Canaveral.

One tool available when selecting a cruise is the Friends of the Earth’s 2012 Cruise Ship Report Card. The report card, the third from the non-profit, ranks 15 major cruise lines and 148 cruise ships for their air and water pollution footprint. The report card allows potential passengers to search by destination, by ship or simply identify the ships with the highest overall grades.

To view the report card, go to foe.org/cruise-report-card.

This year the group handed out its first ‘A’ grade. Disney Cruise Line’s overall grade of ‘A-‘ puts it in the “most improved” category again this year. All four Disney ships have advanced sewage treatment systems and three are equipped to plug in to shore-based power, which enables them to turn off diesel-burning engines. Disney joins five other lines that managed to improve their grades in the past two years.

FOE spokeswoman Marcie Keever said that while many states have no discharge zones near shore, that’s not the case at sea. About the only thing international law prohibits is plastic being discarded into the oceans.

“Beyond three nautical miles, there are very, very few rules, especially for sewage and gray water from sinks, showers and kitchens. It can contain many of the same pollutants that sewage does,” Keever said.

The poor performers

Carnival Cruise Lines, with the largest fleet of cruise ships in the world with 24 vessels, and whose parent company, Carnival Corp., also owns six other cruise lines on the report card, improved from an ‘F’ in 2010 to a ‘D+’ this year. However, Carnival’s grade improved due to improvements for the one ship it operates in Alaska and its installation of shore-based power on two of its ships, Keever said.

Keever said most of the Carnival ships use a traditional marine sanitation device, and while it meets federal standards developed in the 1970s, is an older technology. New systems known as Advanced Sewage Treatment Systems are more expensive, but have more filters and do more to remove pollutants, Keever said.

Friends of the Earth is asking the EPA to pass strong regulatons on sewage treatment.

“Those systems have not been a priority for these ships because they don’t have to install them,” Keever said. “If they pass the costs of new systems on to the customers, it would be the cost of a can of Coke per passenger.”

Miami-based Carnival referred questions about the report card to the Cruise Lines International Association in Fort Lauderdale.

CLIA responds

“Consumers should not choose a cruise vacation relying on Friends of the Earth’s environmental report card, which, like its previous reports cards, lacks basis in fact, science and law. The grades assigned cruise lines and their ships are based upon arbitrary, faulty, and misleading measures,” said David Peikin, Cruise Lines International Association spokesman.

“The global cruise industry employs practices and procedures that are substantially more protective of the environment than are required by regulation. All CLIA member lines must meet or exceed all applicable national and international environmental regulations. We advocate practices that fully protect coastal waters wherever we operate and our members have invested extensively to implement a wide range of innovative environmental solutions that reduce air pollution, treat sewage prior to discharge, and protect air quality,” Peikin said.

Specific environmental stewardship practices, according to CLIA, of member lines include:

Equipping ships with advanced wastewater treatment systems that produce water cleaner than most wastewater treatment facilities in U.S. cities.

Adopting numerous energy efficient measures including switching to low energy LED lights, developing smoother hull coatings to consume less fuel, using recycled hot water to heat passenger cabins and special window tinting that keeps passageways cooler and utilizes less air conditioning. Halogen and incandescent light bulbs have been giving way to LED lights, which last 25 times longer, use 80 percent less energy, and generate 50 percent less heat.

Implementing rigorous recycling programs as many CLIA member lines have comprehensive programs and crew members who are specially trained and responsible for sorting, processing, storing, recycling, and the final disposal of garbage. These programs include paper, glass, plastics, aluminum, scrap metal, fluorescent lamps, batteries, toner cartridges and cooking oil, and even special wastes such as chemicals used in photo processing. CLIA members recycle up to 80,000 tons of garbage each year.

(c)2012 The Palm Beach Post (West Palm Beach, Fla.). Distributed by MCT Information Services.