Ships exceeded discharge limits on PAH’s, PH levels and particulate matter
Alaska’s marine waters are many things to many people and creatures: a source of food, a scenic view, a place to play, a home, a spiritual conduit, an economic driver — a place to dump waste.
It may be unpleasant to consider but discharging waste into the ocean is legal. During the 2023 and 2024 cruise seasons in Alaska, companies self-reported hundreds of clean water permit violations, exceeding limits of polycyclic aromatic hydrocarbons, pH levels and particulate matter in discharges.
“We know these discharges, even when everything is working perfectly, contain pollutants and are hotter and more acidic than our living marine waters,” said Southeast Alaska Conservation Council Clean Water Campaigner Aaron Brakel. “But everything isn’t always working perfectly and that’s scary.”
SEACC gathered data on noncompliance with the Vessel General Permit under the Clean Water Act from the annual reports of 46 heavy fuel oil-burning, ocean-going vessels visiting Alaska, finding 423 violation days in 2023 and 334 violation days in 2024, in Alaska waters. Violation days here represent a single day and a single vessel; a single vessel may have multiple violations in a single day but would count as one violation day, and multiple vessels may have violations on the same day, which would count as separate violation days. Noncompliance on pH exceedances is reported by vessel by month, adding up to 8 violation months in 2024 and 19 violation months in 2023.
“What we learned from the data was the number of voluntary reports of violations in Alaska waters, but the details of the violations are formulaic and incredibly limited,” said Brakel. “We wish we could tell Alaskans how significant the pollution was and whether it was somewhere they harvest, perhaps, but we can’t. There’s not enough information.”
Despite a lack of specificity in reporting exceedances — neither precise times nor locations were required in annual reports — SEACC was able to determine if violations occurred in Alaska waters by comparing reported violation days to vessel tracking data.
SEACC’s focus was on noncompliance with the Vessel Incidental Discharge Act (VIDA) Exhaust Gas Scrubber Washwater Discharge provisions; these violations are unique to vessels burning heavy fuel oil and using scrubbers to comply with fuel sulfur limits imposed by the International Maritime Organization. The key provisions limit the acidity of discharges (pH of no less than 6.0, with exceptions), the concentration of PAHs (50 micrograms per liter), and the turbidity (not greater than 25 nephelometric turbidity units, with exceptions), which relates to suspended particulate matter including heavy metals and ash.
“It may sound insignificant when you’re talking about micrograms per liter or obscure measures like nephelometric turbidity units, but studies show ships burning heavy fuel oil with some scrubber systems are discharging 90 cubic meters of polluted wastewater per megawatt hour or more than 27 million gallons over a 24 hour period,” Brakel said. “And negative impacts have been observed in marine life like urchin larvae at extremely low concentrations.”
Beyond the sparse details of the violations, SEACC also found that none of these hundreds of reports of noncompliance triggered enforcement actions by the Environmental Protection Agency, and there was no indication the State of Alaska was notified of violations, despite terms requiring electronic copies of noncompliance reports to be provided to the Alaska Department of Environmental Conservation.
“The standards are weak, the reporting requirements are weak, and enforcement is weak — non-existent, even,” Brakel said. “We’re not given enough to know how bad it is but, in my experience, a lack of data doesn’t usually obscure good behavior.”
About violations
In (Month), Turbidity exceeded VGP compliance limits on the following days: (list of days (if more than once in a day, the number of exceedances))
Under cause of noncompliance, exceedances were often described as “intermittent short-term” and frequently noted as “associated with EGCS (X)% of the time”
2.2.26.1.3 Turbidity: The washwater treatment system must be designed to minimize suspended particulate matter, including heavy metals and ash. The maximum turbidity (monitored continuously) in washwater must not be greater than 25 FNU (formazin nephelometric units) or 25 NTU (nephelometric turbidity units) or equivalent units, above the inlet water turbidity. However, during periods of high inlet turbidity, the precision of the measurement device and the time lapse between inlet measurement and outlet measurement are such that the use of a difference limit is unreliable. Therefore, all turbidity difference readings must be a rolling average over a 15-minute period to a maximum of 25 FNU or NTU. For the purposes of this criterion, the turbidity in the washwater must be measured downstream of the water treatment equipment but upstream of washwater dilution (or other reactant dosing) prior to discharge. For a maximum of one 15-minute period within any 12-hour period, the continuous turbidity discharge limit may be exceeded by 20 percent.
In (Month), PAH exceeded VGP compliance limits on the following days: (list of days)
2.2.26.1.2 PAHs (Polycyclic Aromatic Hydrocarbons): The maximum continuous PAH concentration in the washwater must not be greater than 50 μg/L PAHphe (phenanthrene equivalence) above the inlet water PAH concentration for washwater flow rates normalized to 45 t/MWh. MWh refers to the maximum continuous rating (MCR) or 80 percent of the power rating of the fuel oil combustion unit. For the purposes of this criterion, the PAH concentration in the washwater must be measured downstream of the water treatment equipment, but upstream of any washwater dilution or other reactant dosing unit, if used, prior to discharge. The 50-μg/L limit is adjusted upward for lower washwater flow rates per MWh, and vice-versa, and the applicable permit limits are contained in Table 7. For a 15-minute period in any 12-hour period, the continuous PAH concentration limit may exceed the limit described above by 100 percent. This is to allow for an abnormal start up of the exhaust gas scrubber unit.
In (Month), pH excursions occurred for more than 1% of operating time by (X) minutes
2.2.26.1.1 pH: The discharge of washwater from the exhaust gas scrubber treatment system must have a pH of no less than 6.0 measured at the ship’s overboard discharge, with the exception that during maneuvering and transit, the maximum difference between inlet and outlet of 2.0 pH units is allowed. This difference is to be measured at the ship’s inlet and overboard discharge.
Background
Heavy fuel oil use
Heavy fuel oil is used by most large ships visiting Alaska; it’s a cheap fuel that poses risks to communities and ecosystems reliant on clean water. Since the International Maritime Organization imposed fuel sulfur limits, many ships have implemented the use of exhaust gas cleaning systems (scrubbers) to continue burning HFO. Scrubbers reduce sulfur content in air exhaust but ships burning HFO still emit particulate matter, nitrous oxides, PAH’s, and black carbon. The scrubbers used to continue burning HFO generate wastewater containing heavy metals, PAHs, nitrites and nitrates, sulfates and particulate matter pollutants.
Harms from discharges
PAHs
- PAHs Are Highly Toxic to Marine Life
- Carcinogenic and mutagenic: PAHs can cause cancer, genetic mutations, and reproductive harm in fish, shellfish, and other marine organisms.
- Lethal to early life stages: Even low concentrations of PAHs can deform or kill fish eggs and larvae — especially concerning for salmon, herring, and forage fish critical to Alaska’s marine food web.
- Long-term exposure risks: Chronic exposure leads to reduced growth, immune suppression, and liver damage in fish and shellfish.
- Settle in sediments: PAHs don’t easily dissolve in water—they bind to sediments and can contaminate seafloor habitats for years.
- Bioaccumulate and biomagnify: PAHs build up in organisms and move up the food chain, potentially affecting whales, seabirds, and humans who consume contaminated seafood.
Turbidity
- Turbidity reduces light penetration, affecting photosynthesis in aquatic plants and algae—foundational organisms in the marine food web.
- Disruption of habitats: Increased sediment in the water can smother sensitive habitats like kelp forests, coral-like structures, and spawning grounds for fish (e.g., salmon and herring).
- Stress on fish and invertebrates: Turbidity can clog the gills of fish and filter-feeders like shellfish, reducing oxygen uptake and food intake.
- Cumulative impacts: Multiple cruise ships discharging turbid effluent over the season can have a compounding effect on local water bodies, particularly in narrow passages or harbors.
- Threats to subsistence resources: Many Alaskans, particularly Indigenous communities, rely on clean ocean water for harvesting shellfish, fish, and marine mammals. Turbidity can reduce availability and safety of these resources.
Lowered pH and acidity
- Lowered pH, which is too acidic, can stress or kill sensitive species like shellfish, salmon fry, plankton, and larvae.
- pH affects species survival: Most marine organisms are adapted to a narrow pH range (typically 7.8–8.4). Discharges that are too acidic (low pH) or too alkaline (high pH) can stress or kill sensitive species like shellfish, salmon fry, plankton, and larvae.
- Toxicity amplification: Altered pH can increase the toxicity of other pollutants. For example, low pH can make metals like copper or mercury more bioavailable and harmful to marine organisms.
- Localized acidification: While ocean acidification is a global problem, cruise ship discharge can create localized acidification hotspots, especially in areas with limited water circulation like narrow straits or harbors.
- Risk to shellfish harvesting: Many Alaska communities rely on shellfish harvesting for food and livelihood. pH disruptions can damage shell formation and survival rates.
Cleaner fuel push
SEACC is advocating for the use of cleaner fuels in Alaska waters. Ships visiting Alaska waters are already equipped to burn cleaner marine fuel oil and switch to burning this fuel when required (see Glacier Bay National Park) or at the operators’ discretion.
Call for cleaner fuel for marine vessels in Alaska waters
The State of Alaska can regulate fuel use and require cleaner fuel to be used. We need to make it clear that clean water is a priority for all Alaskans.
In the news
Avery Ellfeldt wrote about the violations for Alaska Public Media here.
