RICHMOND, Va. (WRIC) — Heavy rains Tuesday evening caused Richmond’s aging sewer system to overflow, dumping raw sewage into the James River.

The sewage situation is an unfortunate side effect of Richmond’s outdated sewer system, which was built over 150 years ago. Unlike many modern systems, the city uses a so-called combined sewage system — one that routes storm runoff and sewage through the same drains and water treatment facilities.

During dry periods and light rains, that doesn’t pose a problem — the city’s waste treatment plants simply handle storm runoff the same way they handle bathroom waste. But during heavy rains, the plant’s aren’t able to handle the excess water, and the rain, along with the raw sewage it’s mixed with, gets dumped directly into the James.

This graphic shows how Richmond’s sewer system handles storm runoff. (Image: Richmond Department of Public Utilities)

Within the last two days, 17 of the city’s 25 combined storm drains overflowed — dumping sewage into the river from Rockett’s Landing to Forest Hill Park.

A 2011 EPA report found that the overflows not only represent a health threat to residents — who should certainly avoid swimming in contaminated waters — but can also damage ecosystems downstream, such as the Chesapeake Bay.

Residents should avoid swimming in water downstream of overflows, which are tracked live on a map provided by the City of Richmond. (Courtesy of Richmond Department of Utilities)

But solving the issue permanently is no easy task, with estimates ranging North of $1 billion for a system-wide replacement. And state support is unlikely to manifest soon, with Republicans in the House of Delegates killing a proposal in 2022 to set a timeline and provide funding for the improvements.