Cruise ships in Washington waters

We signed a voluntary agreement, called a memorandum of understanding (MOU), for cruise ships to help prevent wastewater discharge into state waters 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 and east 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 or graywater 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 of Seattle to review the past cruise season and consider ways to strengthen the agreement. This meeting is open to the public and we publicize it. The annual meeting for the 2018 season was held on April 2, 2019. We presented on an evaluation of water discharges from exhaust gas cleaning systems installed on many of the MOU cruise ships.

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. MOU parties are in the initial stages of drafting amendments agreed upon at the last annual meeting. These amendments include clarity for hazardous waste requirements and updates such as the member cruise lines.

Previous cruise season reports