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How Sanitation and Shellfish Are Connected

Updated: Apr 3

For centuries, the humble shellfish has been a culinary staple and economic lifeblood for many coastal communities in the United States. From the crunch of fried clams in New England to the briny richness of Gulf oysters, these unassuming bivalves have sustained livelihoods and traditions passed down through generations. However, the fate of America's shellfish industry is intrinsically tied to an often-overlooked factor: sanitation. If you love eating oysters, clams, mussels, and other tasty shellfish from America's coasts, you better hope we get a handle on our crap - literally.


In 2023, FLUSH worked on a market research project for the Ocean Sewage Alliance, investigating the fisheries and aquaculture sectors in the coastal US. We were shocked (and delighted) to learn the intricate connection between shellfish and sanitation in the US, and we will explain it below.

A campaign to eat oysters from the US Government (Credit: FLUSH/K Worsham)

The Link Between Shellfish and Sanitation

Shellfish, such as oysters and clams, are filter feeders. They drink water to search for food and filter out microscopic particles, absorbing nutrients along with any contaminants that may be present. This process is efficient for their survival but also exposes them to contaminants and pathogens in the water.


When a community doesn’t have safe access to toilets, poo always ends up in a waterway – somehow, somewhere. Poo can enter from sewage overflows, leaky septic systems, dumping vessels, and storm runoff can introduce harmful bacteria into shellfish harvesting areas. Check out the image below to see how sewage and septic systems can leak into waterways.

How sanitation systems can leech into waterways (Credit: Wildlife Conservation Society)

When the water they're filtering is contaminated with fecal matter-containing bacteria like E. coli, Salmonella, Hepatitis A, and other nasties you don't want to ingest and get sick from. A single tainted oyster or mussel can spread disease through anyone who eats it raw or undercooked.


Untreated sewage overflows aren't the only concern. A 2021 study found that even fully-treated wastewater from sewage plants can expose nearly 60% of coral reefs and 88% of seagrass habitats globally to nitrogen and other nutrient pollution. All that fertilizer getting flushed out is triggering all kinds of environmental havoc on aquatic life.


Just a note - There are oyster bed projects to filter out pollutants and clean waterways - including New York City’s harbor - but we don’t eat those oysters.


A History of Water Pollution and Job Insecurity

For shellfish harvesters, the struggle against waterborne sewage contamination has been multi-generational. Until the 1850s, oysters in the US were common culinary fare. By the 1860s, US cities had started to build sewer systems to handle growing populations while accommodating heavy rainfall, resulting in combined sewers overflowing into nearby waterways when it rained. These overflows were typically put in areas close to oyster beds, resulting in shellfish on the coasts being showered in raw sewage with no treatment until the 1900s. Because these oysters were contaminated, foodborne illness increased significantly, and people stopped eating oysters completely. Entire fisheries were shut down due to contamination, plummeting demand, and overharvesting oyster beds. To bring the industry back, the US Department of Commerce’s Bureau of Fisheries even started launching PR campaigns in some areas to encourage people to eat oysters again. The book The Big Oyster is a good read for learning more about the rise and fall of US oysters.

Some tasty baked oysters from New Orleans (Credit: FLUSH/K Worsham)

This sobering reality has deeply shaped the modern shellfish industry's practices and regulations. The modern Clean Water Act and other environmental regulations from the 1970s and beyond were hard-won victories that finally forced municipalities to clean up their sewage treatment and stop dumping raw sewage into the ocean. Strict water quality monitoring and standards enforce the shutdown of harvesting areas when bacterial levels spike after heavy rains or sewage spills. Harvesting buffer zones prohibit shellfish cultivation near wastewater outfalls or other high-risk areas. Stringent post-harvest decontamination protocols aim to purge any contaminants the shellfish may have ingested. The US has even banned shellfish from most countries because of their perceived insufficient harvesting regulations and food safety concerns; only a handful of countries are on the list. State fishing departments still shut down fisheries for being too close to sewage outfalls.


The livelihoods of shellfish farmers and harvesters depend on securing clean, sanitary waters free of human waste. One contaminated shellfish could shut down entire harvesting operations for months to prevent a foodborne illness outbreak. Millions in losses, just from one little leaky pipe or broken septic system mishap. This is problematic, not least because, in the US, commercial fishing communities are 46% more likely to be impoverished.


In the 1980s, US-based federal agencies (from the Food and Drug Association to the Environmental Protection Agency) and practitioners launched the Interstate Shellfish Sanitation Conference to help manage the growing stringent concerns about clean water and its potential effects on shellfish sold for consumption. It sets detailed guidelines for shellfish on all coasts, including frequency and kinds of water quality testing, acceptable proximity to urban areas and wastewater discharge points, and best practices for harvesting in extreme weather conditions. Sometimes, their teams also work directly with municipalities to build better sanitation practices to help improve harvesting conditions.


Unfortunately, the threat of sewage overflows persists, especially in urban areas overwhelmed by population growth and climate change. According to some studies, aging and poorly functioning septic systems may now be the leading cause of sewage leaking into waterways and coastal areas. It’s a complicated tapestry; one of our interviews for this research mentioned, “Pollution is coming from septic, agricultural, and manure lagoons. Everyone points the finger at everyone else.”


Solving Climate Change’s Troubles

Unfortunately, the challenges of safeguarding shellfish areas are growing more daunting due to climate change. Rising sea levels and increasingly powerful coastal storms have exacerbated flooding in many low-lying coastal regions. This leads to more sewer overflow events where high stormwater volumes overwhelm sewage treatment capabilities and necessitate the discharge of untreated wastewater into the environment as a safety valve. This also happens with septic tanks that can get flooded during heavy rainstorms, resulting in contaminated fields or leeching systems. Prolonged closures of prime shellfish areas can devastate local economies and food traditions rooted in aquaculture.


This complex challenge will require multi-faceted interventions, from modernizing sewage treatment capabilities to mitigate overflows, restoring natural wetland buffers, and pursuing innovative aquaculture methods more resilient to contamination risks. However, without decisive action, the proud traditions of America's coastal shellfisheries face a murky future increasingly muddied by sewage and the rising tides.


Getting human waste out of our waterways and away from critical shellfish areas must be a bigger priority. Many organizations in the US are working on different ways to improve our seafood quality, such as shellfish, including our client for this project! Still, solving this complex problem will always require integrated, multi-pronged solutions. At the higher level, it could include these features:

A fledgling nature-based filter system in Newtown Creek in 2018 (Credit: FLUSH/K Worsham)

What We Love About This Topic

FLUSH loved working on this project and felt it was an important research project that would help progress the sanitation sector. As a sector, sanitation doesn’t always realize some of its intricate intersectoral connections that are valuable. When we learned that the US shellfish industry has a sanitation sector that works on similar goals but for different reasons, sanitation clearly can impact livelihoods and food security in a direct way that many may overlook. We hope this blog helps change that.

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