Michael Nardolilli helps protect the Potomac River. Photograph of Nardolilli by Evy Mages
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Big news this summer for river swimmers: You can now splash around the capital’s famous body of water! Sadly, it’s the capital of France. The Seine is open for swimming; the Potomac and Anacostia remain unsafe. Here’s a look at how they compare.
Paris
Why It’s Polluted: At the Olympics in 1900, athletes swam in the Seine. But over time, pollution accumulated from human and animal waste, boats, and debris. And Paris has a combined sewer system, so wastewater and stormwater flow through the same pipes. By the late 1960s, about 60 percent of the city’s sewage went into the river.
Year Swimming Was Banned: 1923
The Cleanup Plan: In 1990, Paris’s mayor set a goal to open the Seine to swimmers. Efforts picked up in 2015, when the city announced that the river would be swimmable for the 2024 Olympics. Pipes and wastewater-treatment plants were updated, and an underground storage basin was built to help prevent overflows. The city incentivized houses and houseboats to connect to the city’s sewage plant instead of dumping into the water.
What They’ve Spent: The whole cleanup project is estimated to have cost more than $1.5 billion.
Can You Swim There Now?: The Seine was used for events in the 2024 Olympics, though there were some lingering issues from elevated bacteria levels. This summer, three buoyed-off areas opened for public swimming.
DC
Why It’s Polluted: DC’s stormwater system washes water runoff (along with trash and chemicals that get caught in it) into tributaries leading into the Potomac. Most of the city’s river pollution comes from these small waterways, though heavy rain also sometimes causes overflow in sewer systems that combine wastewater and stormwater.
Year Swimming Was Banned: 1971
The Cleanup Plan: DC’s efforts have been more piecemeal. Community groups spearheaded the initiative with river cleanups that continue today. Local municipalities later signed an agreement to reduce pollution and restore the watersheds. In 2011, DC’s Clean Rivers Project began, seeking to reduce wastewater overflows by, among other things, building three overflow tunnel systems. (One has been completed.)
What They’ve Spent: DC’s tunnels are much bigger than Paris’s–part of why our cleanup is costlier. The new sewer systems alone cost more than $3 billion.
Can You Swim There Now?: Swimming remains prohibited in the Anacostia and Potomac rivers and Rock Creek. The goal is to have swimmable rivers by 2032.
Why Can You Swim in the Seine but not the Potomac River?
Paris’s river cleanup is much further along.
Big news this summer for river swimmers: You can now splash around the capital’s famous body of water! Sadly, it’s the capital of France. The Seine is open for swimming; the Potomac and Anacostia remain unsafe. Here’s a look at how they compare.
Paris
Why It’s Polluted: At the Olympics in 1900, athletes swam in the Seine. But over time, pollution accumulated from human and animal waste, boats, and debris. And Paris has a combined sewer system, so wastewater and stormwater flow through the same pipes. By the late 1960s, about 60 percent of the city’s sewage went into the river.
Year Swimming Was Banned: 1923
The Cleanup Plan: In 1990, Paris’s mayor set a goal to open the Seine to swimmers. Efforts picked up in 2015, when the city announced that the river would be swimmable for the 2024 Olympics. Pipes and wastewater-treatment plants were updated, and an underground storage basin was built to help prevent overflows. The city incentivized houses and houseboats to connect to the city’s sewage plant instead of dumping into the water.
What They’ve Spent: The whole cleanup project is estimated to have cost more than $1.5 billion.
Can You Swim There Now?: The Seine was used for events in the 2024 Olympics, though there were some lingering issues from elevated bacteria levels. This summer, three buoyed-off areas opened for public swimming.
DC
Why It’s Polluted: DC’s stormwater system washes water runoff (along with trash and chemicals that get caught in it) into tributaries leading into the Potomac. Most of the city’s river pollution comes from these small waterways, though heavy rain also sometimes causes overflow in sewer systems that combine wastewater and stormwater.
Year Swimming Was Banned: 1971
The Cleanup Plan: DC’s efforts have been more piecemeal. Community groups spearheaded the initiative with river cleanups that continue today. Local municipalities later signed an agreement to reduce pollution and restore the watersheds. In 2011, DC’s Clean Rivers Project began, seeking to reduce wastewater overflows by, among other things, building three overflow tunnel systems. (One has been completed.)
What They’ve Spent: DC’s tunnels are much bigger than Paris’s–part of why our cleanup is costlier. The new sewer systems alone cost more than $3 billion.
Can You Swim There Now?: Swimming remains prohibited in the Anacostia and Potomac rivers and Rock Creek. The goal is to have swimmable rivers by 2032.
This article appears in the September 2025 issue of Washingtonian.
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