Cruise ships in Washington waters

We signed a voluntary agreement for cruise ships to help prevent wastewater discharge into state waters, called a memorandum of understanding (MOU), with the Cruise Lines International Association North West & Canada (CLIA-NWC) and the Port of Seattle on April 20, 2004.

The agreement:

  • Bans wastewater discharges to Washington state waters from all cruise ships
    • Except discharges treated with advanced wastewater treatment systems (AWTS).
  • Allows us to inspect the wastewater treatment systems on each vessel
  • Requires cruise lines to sample and monitor wastewater discharges from their ships
We most recently accepted amendment proposals through Dec. 4, 2017. The MOU parties consider updates every three years.

See a problem?

  • Immediately report MOU non-compliance to: 425-649-7000 (available 24 hours a day).
  • Immediately report “upset of disinfection" to Washington State Department of Health at 360-236-3330 (8 a.m. to 5 p.m.) or 360-786-4183 (after hours).

Cruise liners help protect Washington's marine waters

The MOU prohibits cruise ships from discharging blackwater (from toilets) and graywater (from sinks and showers) to Washington waters, unless the discharges are treated with advanced wastewater treatment systems (AWTS).

Who does the agreement cover?

The agreement covers only cruise lines that are members of the CLIA-NWC and their large cruise ships. This means it does not cover vessels that carry paying passengers. The following vessels are not covered:

  • Smaller passenger ships or boats
  • Washington State Ferries
  • Alaska Marine Highway ferries
Large cargo ships are subject to EPA’s Vessel General Permit.

Requirements for cruise ships

Ships that discharge must meet other stringent requirements, including:

  • Advanced notification and documentation from ships planning to discharge via AWTS
  • No discharges within a half mile of shellfish beds
  • Limits on certain pollutants, with specific sampling, testing, and reporting requirements
  • Continuous monitoring for turbidity (murkiness) and disinfection
  • Disinfection of all discharges, with capability to shut down immediately

Area covered by the agreement

The agreement applies to Washington marine waters, including:

  • All waters south of the Canadian border
  • Ocean waters up to three miles from shore
  • Olympic Coast National Marine Sanctuary

Almost all cruise liners have opted to not discharge any sewage while in Washington waters covered by the MOU. Since 2012, every CLIA-NWC vessel in Washington has followed this practice.


Each year the cruise lines must send us an annual report on their ships' wastewater practices. The MOU allows us to inspect each vessel's wastewater records and equipment to verify compliance.

MOU amendments and public review

Each year, we meet with the CLIA-NWC and the port to review the past cruise season and consider ways to strengthen the agreement. This meeting is open to the public and publicized by Ecology.

Annual Cruise MOU Meeting
April 2, 2019
11:30 a.m. – 12:30 p.m.
Port of Seattle, Pier 69
Draft agenda

The MOU is open for proposed amendments every three years (last open in 2018), with approval by all three parties. We've amended the MOU six times.

Accountability through a voluntary solution

The federal Clean Water Act reserves authority over vessel sewage to the U.S. government.

Currently, ships and boats may release untreated sewage three or more miles from land. Within three miles they may discharge through federally-approved equipment that provides a certain level of treatment. A special provision allows Alaska to require AWTS. 

The MOU enables the cruise industry to thrive in Washington while providing public accountability for the ships' environmental performance. 

Previous cruise season reports