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After Ellicott City flood, calls to stop development, but how does it really impact flooding?

Posted at 6:31 PM, May 30, 2018
and last updated 2018-05-31 10:45:00-04

After the devastating flooding in Ellicott City over the weekend, there are renewed calls to stop development upstream.

Resident Dave Mullen stood on Ellicott Mills Dr. during rush hour Tuesday night, holding a sign that reads "No new development. You are ruining history."

"I don't know what to think. Would the town have flooded? I mean probably but would it have been catastrophic these last two events? Only logic and reason would make you realize that that's not the case. There's no way that these floods would be this catastrophic without all this development," Mullen said. 

But how much of that is true?

"The threat is natural and I think we exacerbate that threat through human or man-made factors," University of Maryland Associate Professor Marccus Hendricks said. 

He studied urban flooding and development and says they are definitely connected. 

"It increases the amount of water, the velocity or speed of the water, new water, as well as overwhelming the local drainage and storm water infrastructure not having the capacity to actually manage the water, so the water has to go somewhere and so it goes into people’s homes and businesses," Hendricks said. 

History is not as clear. Howard County Historical Society executive director Shawn Gladden says the city has had 17 significant floods since being founded in 1772 as a thriving industrial mill town. 

"Building on top of water, tributaries like this was common for mill towns and beneficial," Gladden said. "It's a granite valley built on top of three rivers; flooding is going to happen."

The worst was the 'Great Flood of Maryland' in 1868. It was a combination of two different types of floods that impact Ellicott City: the swelling and rising of the Patapsco River and the overflow of the Tiber and the Hudson.

"In 1868, the flood waters were 24.5 feet high and 42 people lost their lives. The second worst was in 1972 when the water was 14.5 feet high and 7 people were killed," Gladden said. "We are still waiting to see where this flood sits. It was definitely higher than 2016."


Gladden says the 1972 flood was caused just by the Patapsco swelling, which is why there was no rushing water. The 2016 and 2018 floods were caused by the Tiber and Hudson overflowing, causing the rushing water. 


TAKE A LOOK: Ellicott City's long history of devastating floods


Since 2016, the county has made repairs and built storm walls, and has lots of other projects in the works. 


"Any building that goes on, it cannot disturb the flow of water; things like steep slopes or existing wetlands or streams and any development in the county now have to be built to a 100-year stormwater requirement," county councilman Jon Weinstein said. "The repairs that were affected since they will make the recovery a little easier."

He says it's a process that will take years to fully complete. They also requested an in-depth study of the watershed to see what impact development played on the 2016 flood. According to the study, looking at a 100-year flood, there would be an average 23% decrease in feet of water only if the entire watershed was not developed at all, except for Main St. It's important to note that 2016 and 2018 have both been called 1,000-year floods, which is not included in the study. 

"Development certainly plays a part in run off and storms, but this storm was worse than the last storm. It was more rain. It lasted long and it followed a weeks worth of saturating rain," Weinstein said. 

As history shows, after the floods comes the rebuild. 

"One of the things about Ellicott City is that after very one of these flood events, it is rebuilt. And obviously for people who live in and around Ellicott city, it is a special place and it's very hard to not look at what happens after these events and not want to rebuild," Gladden said. "After every major look in Ellicott City's history, there's always been a call by residents ­who live in and around Ellicott City to stop development, even after 1868."

Everyone agrees there are projects to mitigate flooding. The county has over a dozen other ideas in the works to continue prevention set out after the 2016 flood. It's all to return Ellicott City to the vibrant and resilient town it's been for hundreds of years.