Sewage. It’s nasty stuff, and it should be treated to prevent potential health and environmental impacts. I am often frustrated by the extremely weak laws that regulate sewage dumping from ships, and even these weak laws often aren’t adhered to. 

Weak Regulation

Sewage, as defined by The International Convention for the Prevention of Pollution from Ships, is “the drainage and other waste from any form of toilets and urinals, drainage from medical premises, spaces containing live animals and other wastewaters missed with these drainages.”

There are two main problems with current international sewage regulation. First, ships are allowed to dump untreated sewage into the ocean as long as they are further than 12 nautical miles from the coast. Think about that. Raw sewage can be dumped into the vast majority of the ocean.

Within three nautical miles of shore, vessels of more than 400 gross tons and passenger vessels certified to carry 15 people or more must treat sewage using an approved sewage treatment plant. The plant must meet specific treatment standards for total suspended solids, fecal coliforms (indicator organisms that suggest the presence of other bacteria) and other harmful discharges. When ships are between three and 12 nautical miles from shore, they must—at a minimum —disinfect their sewage using an approved sewage treatment system. While better than no treatment at all, disinfection is outdated and inadequate now that [most] ships have the ability to use more advanced and effective sewage treatments.

The second problem with current international sewage regulation is that the approved sewage treatment plants needed to meet these requirements are not actually doing their jobs. A 2017 study concluded that 97 percent of ships tested did not meet sewage effluent requirements, despite using approved plants. Not only can ships dump raw sewage outside of 12 nautical miles from shore, but 97% are dumping sewage that does not meet legal requirements within this range. The study revealed that most of these ships didn’t come remotely close to meeting legal standards, with astronomical levels of dangerous contents like fecal coliforms.

How This Impacts the Marine Environment

Not only is untreated sewage gross, these discharges can lead to some major issues for our ocean, including oxygen depletion and the spread of pathogenic bacteria and viruses. It can also increase nutrient levels in the surrounding ecosystem, which can lead to toxic algal blooms, dead zones and fish kills that can cause harmful disturbances throughout food chains. Additionally, people consuming marine resources can contract a range of illnesses from contaminated waters, which is of particular concern considering the number of Indigenous peoples whose diets rely heavily on marine resources.

Slow but Promising Change

Thanks to the leadership of Norway, work has commenced to require the monitoring and maintenance of sewage treatment plants’ performance, and enable the enforcement of plant effluent requirements throughout the lifespan of the system. This is taking place at the International Maritime Organization, a specialized agency of the United Nations responsible for regulating shipping. These changes are critical to reducing the environmental and human health risks posed by sewage discharge from marine vessels.

Alaska has Already Shown That Improvement is Possible

The State of Alaska went through a similar process 20 years ago, when a state study reported 100% noncompliance rates from ships, meaning that none of the 36 sewage samples from 12 passenger ships met the federal effluent certification standards that were in place. Federal and state legislation applying to Alaska state waters created new effluent standards that effectively mandated the use of Advanced Wastewater Treatment Systems for passenger vessels with capacity for 250 or more lower berths. The regulatory scheme also required the establishment of sampling and inspection programs for passenger vessels with capacity of 50 or more lower berths in Alaska.

In 2018, more than 96% of sewage sample results were in compliance with certification standards for all ships, showcasing promising improvement. 

What Next?

Sewage should be treated, no matter where it is dumped in the ocean—and treatment systems should work properly. Ocean Conservancy is working with a variety of stakeholders to strengthen these regulations and ensure treatment systems perform properly in order to best protect our ocean’s fragile ecosystems and the communities and marine wildlife that depend on them.