Cruise ships in Washington waters

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Annual meeting — April 5

Join us on April 5 from 9 – 10 a.m. We'll provide a review of the 2022 cruise season and an update on the MOU.

Annual meeting on cruise ships in Washington waters

A voluntary agreement, called a memorandum of understanding (MOU), helps prevent wastewater discharges from large cruise ships into state waters. We first signed the MOU with the Cruise Lines International Association North West & Canada (CLIA-NWC) and the Port of Seattle in 2004.

The waters subject to the MOU include Puget Sound and the Strait of Juan de Fuca south of the international boundary with Canada; along Washington’s Pacific Coast extending three miles seaward; and the Olympic Coast National Marine Sanctuary.  

Cruise vessel sailing

Cruise vessel sail from Elliott bay.  Photo courtesy - Port of Seattle

The agreement:

  • Bans wastewater discharges to Washington state waters from all cruise ships
    • Except discharges treated with advanced wastewater treatment systems (AWTS) and outside Puget Sound No Discharge Zone.
  • Allows us to inspect the wastewater treatment systems on each vessel.
  • Requires cruise lines to sample and monitor wastewater discharges from their ships.                               

See a problem?

  • Immediately report MOU non-compliance to: 206-594-0000 (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) and outside the Puget Sound No Discharge Zone.

Who does the agreement cover?

The agreement covers only cruise lines that are members of the CLIA-NWC. This means the MOU does not cover all vessels that carry paying passengers. The following vessels types are not covered:

  • Non CLIA-NWC member line smaller passenger ships or boats carrying less than 249 passengers.
  • Washington state ferries (state ferries pump their sewage to on-shore treatment plants)
  • Alaska Marine Highway ferries
  • Large cargo ships, which are subject to EPA’s Vessel General Permit.

Requirements for cruise ships

Ships that opt to legally discharge via an AWTS 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 or within the Puget Sound No Discharge Zone
  • 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 lines 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. The MOU also allows us to complete random onboard equipment and records inspections on an annual basis. 

 Annual meeting

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. All three parties must agree in order to amend the MOU. The 2021 meeting took place online on August 24.

During this meeting, the MOU partners reviewed the amendments proposed earlier this year, followed by a question and answer session open to public. 

The partners considered two amendments to the MOU. We invited public comments on the amendments from Feb. 17, 2021 to March 19, 2021. We received several comments

  • The partners adopted an amendment to make the MOU consistent with the Puget Sound No Discharge Zone.
  • The partners also agreed to study the discharges of scrubber wash water from air pollution control systems. The partners referred to a 2018  evaluation of water discharges from exhaust gas cleaning systems installed on many of the MOU cruise ships. Eleven organizations had proposed that the MOU prohibit scrubber wash discharges into Washington waters. Ecology spoke in favor of the amendments.

 Stay informed

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Previous cruise season reports