The cruise ship program has received an increased number of complaints and questions regarding cruise ships and possible wastewater discharges. Public complaints have included foam or sheen like appearance on the water surface, and excess air emissions from ships.
What is the source of foam on the surface of the water?
Foam may be from natural sources such as algae blooms or from human sources. Foam has been observed from cruise ship air Exhaust Gas Cleaning Systems (EGCS or scrubbers) discharges by the program. These systems can use a very large amount of water with pumps mixing seawater prior to discharge. Other possible ship sources of foam are from propulsion mixing natural sources, cleaning, and other wastewater discharges. It may be difficult to identify the source of any foam.
How do I report a complaint?
Is there evidence that cruise ships are a source of bacterial contamination?
Currently there is no evidence of cruise ships being a source of bacterial contamination. Scrubbers are not a source of bacteria. Large cruise ships must operate with wastewater treatment technology designed to filter and disinfect wastewater (sewage and graywater). Regular sampling and inspections are performed to monitor wastewater treatment. The general permit requires them to meet the raw shellfish water quality criteria at the point of discharge. There is no mixing zone for bacteria for large cruise ships.
Small cruise ships and ferries must have working wastewater treatment equipment and must minimize discharges near shore. They do not have permit limits and have relatively low volumes of wastewater discharges.
What are Exhaust Gas Cleaning Systems (EGCS or Scrubbers)?
Exhaust Gas Cleaning Systems are pollution control systems designed to remove pollutants from exhaust. Primarily, these systems are designed to extract sulfur oxides (SOx) from the exhaust. By installing these systems, vessels can be compliant with federal SOx emission regulations without using low-sulfur fuels. Exhaust Gas Cleaning Systems have been installed on many cruise ships operating in Alaska in the last three years.
Who regulates Exhaust Gas Cleaning Systems?
The US Environmental Protection Agency (EPA) regulates the EGCS discharges and exhaust sulfur requirements in the United States. EGCS discharges are currently regulated in the EPA Vessel General Permit. EGCS discharges are part of the 2018 Vessel Incidental Discharge Act, EPA and US Coast Guard will be updating EGCS requirements.
How do Exhaust Gas Cleaning Systems work?
Scrubbers are a form of pollution control equipment. Scrubbers use chemical or physical processes to remove pollutants from the exhaust gases. Open loop scrubbers use seawater and discharge the wash water. Closed loop scrubbers are an internally confined process using chemical reagents to selectively remove pollutants of concern. Reagents must be recharged or off-loaded as a waste stream and replaced. There can also be hybrid systems using more than one method. Scrubbers have limitations and must be adequately maintained, monitored, and operated in order to comply with a complex set of regulatory requirements.