The Story Behind the Flooding in Charleston, SC

Charleston flooding after Hurricane Matthew in October 2016. Photo by USCG Petty Officer Alexandria Preston

If you’ve ever experienced a rain storm in Charleston, then you probably know about the flooding problem. This pretty much happens every time it rains, but it is especially bad at high tide, when the sewers are filled with sea water before it even starts raining. During the highest tides of the year, commonly referred to as “King Tides”, the Charleston peninsula is known to flood even on the sunniest of days, as water from the harbor simply overflows into the streets.

Charleston floods so bad that you can easily float your car if you are not careful about where you drive when the streets are flooded. As a general rule of thumb, if you aren’t sure whether the water is shallow enough to drive through, it’s definitely too deep. It’s also important to keep in mind that if the flood water is tidal then it is salty and can damage your car.

Flooding in Charleston, SC in September 2020.

The flooding problem does seem to be getting worse over the years, but the issue dates back to the city’s roots. Charleston and the surrounding area is geographically a salt marsh, lovingly known as the Lowcountry. There is an inherent problem with flooding that is tied into the very choice to build a city in this location.

Part of Charleston’s development involved the filling in of marshlands around the peninsula in order to make more room for building. The marshes were filled in with ballast from ships coming in from the Atlantic, who would replace the weight with cargo. Once the marsh was full enough for whatever standards they may have had at the time, it was paved over and built on.

To give those familiar with Charleston a mental picture of this: East Bay Street was waterfront property during the city’s inception, serving as the site of the city’s first wharf. It was later filled in and now sits about half a mile from the harbor.

Couple the city’s swampy location with the fact that the region is prone to intense rainfalls during the summer season, and you’ve got a recipe for a very wet town. The rain in Charleston comes on quickly on the hottest of days, drenching everything and everybody with torrential downpour that only lasts a short while but completely overwhelms the meager drainage systems that the city does have.

Alas, there is nothing that can be done about the location of Charleston now, so we’ll have to live with the weather and try our best to do something about the flooding. Plus, we’re all glad that Charleston is located where it is, because as we know it’s an absolutely beautiful place.

Flooding in Charleston, SC in September 2020. Featuring our friend Kevin Early of The High Divers. Photo by Brad Nettles / Post & Courier.

Possible Solutions

The eventual sinking of Charleston was clearly not considered as a factor when the city was first built, and in fact nobody even attempted to do anything about the flooding until the 1800s. By then, though, it was too late for the most important thing that can be done, which would be to go back in time and fill in the entire peninsula by another six feet prior to building anything on it.

Another, less extreme solution that still requires a time machine would be to install bigger drainage pipes in the city so that the rainwater is at least able to drain faster when the sewers are not already full of tidal waters. This, of course is not possible without completely gutting the city and building new drains from scratch, and the streets are so narrow that it doesn’t allow for much room to work. Plus, doing that wouldn’t even solve the issue of the sea water that fills the pipes at high tide.

Charleston’s sea wall under construction in 2021.

The City of Charleston is currently in the process of doubling the height of the sea wall surrounding the Southern tip of the peninsula, but that will only do so much. Raising the sea wall only really helps with storm surge and the type of tidal flooding that involves the water seeping over the marsh and into the streets. Again, it does nothing for the sewers that are already filled with water that sometimes flows out into the street around it.

A second plan that the city has set in motion is to install pump stations in the areas that are most prone to flooding that will help to remove the water before it can accumulate. The city claims that these pump stations will be able to move water to the harbor fast enough to significantly help with the flooding, even at high tide.

Naturally, there are limitations to this that we have the weather to thank for, and the city has already stated that these pump stations will not be effective during tropical weather events. In those cases, we’re on our own.

See a drone video of coastal flooding and storms in Charleston from November 2021 below

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