Frequently asked questions

What is a No Discharge Zone (NDZ)?

A No Discharge Zone (NDZ) is a designated body of water where the discharge of sewage (blackwater/toilet waste) from boats, whether treated or not, is prohibited.

Previously, federal regulations allowed treated sewage to be discharged anywhere in Puget Sound, and untreated sewage could be discharged as long as the boat was more than three miles from shore.

With the NDZ now in effect, no boat of any kind or size can discharge sewage wastewater anywhere within the zone. All boats and vessels have to store their sewage until they can safely dispose of it at an onshore or mobile pumpout facility, or hold it until it can be discharged in the open ocean beyond three miles from shore.

The United States Environmental Protection Agency (EPA) Vessel Sewage website has more information on NDZs. There are 91 NDZs in 27 states. A full listing of these NDZs is provided on EPA’s NDZ website.

​When did the Puget Sound NDZ take affect?

The NDZ for Puget Sound and certain adjoining waters came into effect on May 10, 2018, with the adoption of Chapter 173-228 WAC in April 2018. However, certain commercial vessels have a five-year delay before the rule begins. There is no change for graywater discharges.

Which waters are included in the NDZ?

The boundaries include all:

• Inland marine waters of Puget Sound, Lake Washington, and all the water bodies that connect Lake Washington to Puget Sound.
• Marine waters east of a line between the New Dungeness and Discovery Island lighthouses, east of Port Angeles and Victoria.
• The San Juan Islands in the north and South Puget Sound and Hood Canal. (See map)

Why can't we rely on marine sanitation devices to treat boat waste?

The performance of most commonly used marine sanitation devices (MSDs) can be inadequate for treating sewage or for insuring Puget Sound is protected. An EPA study documented that fecal bacteria levels in discharge from MSDs can be several thousand times higher than Coast Guard standards for MSDs.

MSD requirements for Type I and Type II also do not match our state water quality standards, which are more protective of human health and the environment than federal standards. Vessels can also potentially discharge directly to sensitive water bodies, such as shellfish beds.

Land-based treatment systems include fixed outfalls with limits that must meet water quality standards and regular monitoring.

What do marine sanitation devices do?

There are three types of marine sanitation devices (MSD), and each works differently:

• Type I: Grinds and disinfects sewage, and should control fecal bacteria to 1,000 bacteria colonies per 100 milliliters of water.
• Type II: Digests sewage with a septic process, and should control fecal bacteria to 200 bacteria colonies per 100 milliliters of water.
• Type III: Provides a holding tank for disposal of sewage other than to water, most commonly by pump-out for delivery to an on-shore wastewater treatment plant.

How do Type I and Type II discharges compare to on-shore treatment?

There are several differences:

• Studies on MSD treatment show an average of 2 million fecal coliform for Type II MSDs and a simulated study shows an average of 82 fecal coliform for Type I MSDs, although likely higher in real world co​nditions; the water quality standard for most of Puget Sound is a geometric mean of 14 with no more than 10 percent higher than 43
• On-shore plants must limit bacteria to meet the water quality standards at a fixed deep water outfall already closed off for shellfish harvesting. On-shore treatment typically average around 20 fecal coliform (15 for the Mukilteo plant in 2016)
• On-shore treatment plants must monitor their discharges and ensure their process performs according to required standards
• There is no monitoring or maintenance required after an MSD is installed

How does a Puget Sound NDZ affect boaters?

Recreational boaters with existing holding tanks will continue to hold their sewage (blackwater) within the NDZ area, and either pump out their sewage for treatment at an on-land wastewater treatment plant or discharge outside of the NDZ and beyond three miles. Recreational boaters with Type I or Type II MSDs will need to add a holding tank and not discharge any treated or untreated sewage in an NDZ.

Commercial vessels will also have to hold their sewage, treated or untreated, while in an NDZ and either pump out their sewage for treatment at an on-land wastewater treatment plant or discharge outside of the NDZ and beyond three miles or outside of the NDZ with a certified Type II MSD.

With so many vessels with holding tanks, why is a NDZ necessary?

Parts of our marine waters are more than three miles from shore. Without a NDZ vessels can discharge sewage in these areas. Also, some commercial and recreational vessels have Type II MSDs which typically do not treat sewage to the same standards as land-based systems and are not well-maintained or operated. The poorly treated or raw sewage discharged from vessels on Puget Sound puts water quality and public health at risk.

What about graywater?

The NDZ does not affect graywater discharges. The Clean Green Boating website has information on best management practices and requirements for graywater, as well as other potential discharges such as fueling, bilge care, and hull cleaning.

How much does it typically cost to pumpout a vessel?

Most recreational pumpouts are either free or $5. Mobile pumpouts boats may charge more for the convenience of coming to you. Commercial vessel pumpout costs vary, typically to cover the cost of sending the sewage to land-based treatment.

How has Ecology evaluated whether a NDZ is needed?

Over a five-year period, we evaluated the appropriateness and feasibility of establishing the NDZ in all or parts of Puget Sound. Although not required by EPA for an NDZ petition, Our work produced more than nine reports on various topics such as vessel populations and sewage management, Puget Sound conditions and modeling, pumpouts, cost/benefit, and implementation strategies. We reached out extensively to stakeholders and provided a draft petition and obtained input in 2014.

Where did this idea come from?

Establishing a NDZ has been a near-term action on the Puget Sound Partnership's Action Agenda and is highlighted in the Washington Shellfish Initiative. Ecology researched and prepared the NDZ petition with a grant from the Washington Department of Health, funded by EPA’s National Estuary Program.

How is the government implementing the NDZ?

Our approach is first focused on outreach and education. We are working with partners in n NDZ Enforcement Committee and NDZ Outreach and Education Committee to help spread the word about our new rule. However, it is the law. Your sanitation device may be inspected and you could be fined (Chapter 90.48 RCW, Chapter 173-228 WAC). Ecology and the United States Coast Guard may enforce this rule by using the enforcement provisions in Chapter 90.48 RCW and federal provisions.  In addition, other federal, state and local agencies may provide enforcement, as authorized.  

How does a vessel operator comply with a NDZ?

The requirements for vessel operators are described in 33 CFR 159.7(b) (PDF) (2 pp, 190 K). The regulations allow for four methods of securing a Type I or II marine sanitation device (MSD) while in a NDZ, including:

• Closing the seacock and removing the handle;
• Padlocking the seacock in the closed position;
• Using a non-releasable wire-tie to hold the seacock in the closed position; or
• Locking the door to the space enclosing the toilets with a padlock or door handle key lock.

For Type III devices, the following options are available:

• Use stationary pumpouts, mobile pumpouts, pumping services (barges, trucks), or discharge outside the NDZ following requirements.

Vessels without installed toilets must dispose of any collected sewage from portable toilets or other containment devices at facilities in a manner that complies with state law (ashore in proper facility).

Do we allow municipalities to discharge raw sewage to Puget Sound?

No! State law prohibits the discharge of untreated sewage to Puget Sound and other surface water bodies in the state. We regulate wastewater treatment plants through individual water quality permits developed to ensure that discharges comply with the state’s water quality standards.  We also review engineering documents for proposed sewage facilities in the state and only approve proposals that protect state water quality. 

We recognize that some communities have old collection systems that were originally designed in the early-to-mid 1900s to quickly convey combined sewage and stormwater runoff to surface water for disposal. Over the last few decades these communities have taken significant steps to control their Combined Sewer Overflows. They are complying with a 1985 law that required the “greatest reasonable reduction in combined sewer overflows”.  We continue to work with these communities to enforce state and federal regulations developed to minimize the water quality and public health risks associated with this legacy issue.