New Paper from The Nature Conservancy Reveals Sewage Pollution Threatens Ecosystems Globally

Issuing a Call to Action for Environmentalists to Join Public Health and Development Sectors to Reimagine How to Manage Sewage for People and Nature

For millennia, people have preferred an “out of sight, out of mind” approach to dealing with sewage. Indeed, this mindset has influenced both habitat conservationists and environmental scientists who have generally dismissed sewage pollution as a local but not global problem. New research published today in the journal Biological Conservation from The Nature Conservancy and partners overturns this conventional thinking and shows that sewage contamination is not only widespread in terrestrial, marine, and freshwater ecosystems, but that it also negatively impacts biodiversity and benefits for nature and people, such as coastal security and fisheries.  The authors assert to solve this problem we must break traditional silos and work internationally across sectors to stop this killer threat.  

“There are 4.5 billion people who don’t have access to safe sanitation and sewage pollution is a far greater threat than people realize; 80% of all sewage is discharged untreated into the environment. That, combined with poorly designed and poorly maintained sanitation systems degrades the health of lakes, rivers, and coastal waters on which people and wildlife depend,” said Dr. Stephanie Wear, senior scientist and strategy advisor at The Nature Conservancy and lead author of the study. “Results of this work show that we must recognize sewage pollution as a major threat to habitat degradation across all biological realms.  Solving this global problem requires cross sector collaboration with sectors including conservation, human health, technology, and development to abate this threat.” 

Results of this recent paper also highlight surprising vulnerability in ecosystems thought to be resilient to sewage.  For decades, people have dumped sewage into salt marshes and mangroves with the understanding that these environments act as natural filters and could naturally treat the sewage without being negatively impacted. This understanding is wrong. Excess nitrogen increases erosion and susceptibility to climate change in wetlands - habitat that is essential for coastal protection and healthy fisheries. 

This study shows that across the globe, high levels of sewage pollution likely occur in coral reefs, salt marshes, and fish-rich rivers in both developed and developing countries.  For example, more than 30% of salt marshes around the world experience high levels of sewage contamination. Countries with high to very high levels of sewage contamination include China with 4,176 km2 (76% of Chinese marshes) of marshes impacted and the United States with 3,211 km2 (17% of U.S. marshes) of marshes impacted. Smaller regions or countries with sewage contamination in a high percentage of their marshes include Italy (72%) and the United Kingdom (44%). 

“The conservation paradigm must change,” said Dr. Wear. “Sewage pollution can no longer be dismissed as an occasional local threat, but now must be considered among the major global threats to our environment.  The good news, is that we can solve this problem.”

While the threats are immense – innovative solutions exist that provide exciting opportunities for a long list of co-benefits. Among the recommendations included in the paper to address this problem are looking at waste as a resource. Instead of polluting the environment, we can turn it into valuable resources – drinking water, fertilizer to grow crops, and fuel to power our lives.

Media Resources
Interview Opportunity: Stephanie Wear, the lead author of this study, is available for interviews. 
Journal Article: Sewage pollution, declining ecosystem health, and cross-sector collaboration 
Photos: Photos of sewage pollution are available upon request.

The Nature Conservancy is a global conservation organization dedicated to conserving the lands and waters on which all life depends. Guided by science, we create innovative, on-the-ground solutions to our world’s toughest challenges so that nature and people can thrive together. We are tackling climate change, conserving lands, waters and oceans at an unprecedented scale, providing food and water sustainably and helping make cities more sustainable. Working in 76 countries and territories—37 by direct conservation impact and 39 through partners—we use a collaborative approach that engages local communities, governments, the private sector, and other partners. To learn more, visit or follow @nature_press on Twitter.