Experts weigh in on development's impact on Ellicott City flooding

Main Street in Ellicott City is shown in March, 10 months after the deadly 2018 flood. Some business, such as Syriana Cafe, have reopened. Some new business have moved in, but several buildings remain unoccupied with businesses choosing not to return.
Main Street in Ellicott City is shown in March, 10 months after the deadly 2018 flood. Some business, such as Syriana Cafe, have reopened. Some new business have moved in, but several buildings remain unoccupied with businesses choosing not to return. (Jeffrey F. Bill / Baltimore Sun Media Group file)

Len Berkowitz had been on Main Street in Ellicott City for nearly 40 years.

He and his wife, Sherry, owned Great Panes, a glass staining shop. But the devastating flood a year ago convinced them it was time to move.

Podcast: After two floods in three years, Ellicott City reckons with its future

They did not leave after a 2016 flood deemed a “1,000-year storm” by experts — meaning it had a 0.1% chance of occurring in a single year— hit the town. The event pushed them into debt, left two people dead and caused millions of dollars in damage.

The couple poured money into the shop and soon reopened.


Then the 2018 May flood hit, another “1,000-year storm,” which destroyed their shop again.

The Berkowitzes, who lacked the finances to rebuild, moved their home and business out of the town.

Howard is pursuing a plan that could cost as much as $140 million to alleviate the situation. But experts say the mission to fully omit flooding in the town is impossible.

Historic Ellicott City is surrounded by granite and sits at the bottom of a valley next to the Patapsco River. And its site once made it a thriving mill town. But now, its natural geological conditions coupled with decades of development that frequently went without sufficient stormwater management regulation has exacerbated flooding, experts say.

After months of waiting to learn the fate of flood reduction efforts in historic Ellicott City, Howard County decided on an expensive proposal.

But the intense flooding that has twice ravaged the historic district in two years is not unique to Ellicott City. It’s part of a larger, national trend where urban development not paired with adequate stormwater management drainage results in calamitous floods, according to Ed Link, a researcher at the A. James Clark School of Engineering at the University of Maryland, College Park.

Before urban development, trees, grass and shrubs served as a natural stormwater management system where rain collected and, when necessary, flowed into streams and rivers to mitigate potential floodwater.

But when development became more sophisticated, natural greenery was swapped with impervious surfaces and often not accompanied by adequate stormwater management systems and facilities.

“When you develop an area and you pave it, you change the hydraulic characteristics pretty dramatically,” Link said. Builders are supposed to “put in storm drainage systems to cope with that.”

Stormwater management can include culverts, gutters, tunnels and dry ponds.

“But when you have continued development over decades and the storm [management] systems don't keep pace with that change, you end up with a situation like Ellicott City, Houston and every major urban area” that suffers from intense flooding. “This is a very common problem across the country,” Link added. “It’s only news when a very rare water event occurs.”

And it could get worse.

A 2017 National Climate Assessment found that heavy rain events are increasing nationally, and the greatest increases will occurr in the Midwest, upper Grat Plains and the Northeast.

Though the idea of stormwater management has existed since the mid-20th century, Maryland did not implement statewide requirements until 1984. This means development in Ellicott City prior to 1985 went without stormwater management regulations — 31% of the land was developed with no stormwater management requirements. The standards enforced by the county evolved over time. Currently, the old Ellicott City watershed’s stormwater management standards include the “100-year.”

Link said Howard’s “100-year” standard is substantial when compared to other localities. He noted New Orleans, a city no stranger to intense storms, which requires new drainage improvement projects to be designed to the 10-year standard. Minimally, Maryland requires environmental site design standards for development to be based on a one-year storm, according to Jay Apperson, a spokesman for the Maryland Department of the Environment.

Howard does not allow most developments to be exempt from installing stormwater drainage. Only smaller structures, like sheds, patios and garages, are given waivers. Roughly 20 permits were given each year between 2015 and 2017, a Department of Planning and Zoning official said at a County Council meeting earlier this month.

Howard prohibits developers from paving, grading or removing trees in areas like wetland buffers, steep slopes or near streams, unless it is deemed a necessary disturbance to build “roads, driveways, utilities, trails, pathways or stormwater management facilities” that is needed for “reasonable development” of the property. Under an older version of the law, the Department of Planning and Zoning could require developers to pursue the “least damaging designs.”

Councilwoman Liz Walsh, whose district includes Ellicott City, earlier this year filed legislation to strike the exemption which she previously deemed a “loophole” in the protection of wetlands. The measure as intended failed. The passed version made it so the Department of Planning and Zoning must require developers to pursue the “least damaging designs” when disturbing these areas.

Walsh, a Democrat, has been “hypercritical” of recent development in the historic district because of a “long, entrenched practice” of the Department of Planning and Zoning to waive “basic environmental regulations” including those that allow developers to disturb stream buffers, remove old trees and clear scenic buffers, she said.

“It’s like there's no grownup involved. The plans come in to [DPZ] with the entitlement that they will get whatever they need to get to put as many houses in acreage that they think they’re entitled to put,” Walsh said.

Walsh cited the county’s recently approved project that would remove at least 28 trees located at the confluence of the New Cut and Tiber-Hudson streams. The trees’ removal is needed to construct two stream walls and replace a water main, according to a summary submitted to the Historic Preservation Commission.

“That was stunning to me,” Walsh said. “Even our own county projects don’t comply with basic laws.”

Deputy Director of the Department of Planning and Zoning Mark DeLuca in an email said the move is an “emergency project” and the trees will not be replaced because the “root systems will damage the [stream] wall.”

As a sophomore at Marriotts Ridge High School, Michael Wade has been researching flood reduction strategies specifically for Ellicott City.

While Walsh acknowledges there aren’t stormwater management standards “in effect in some of those older neighborhoods,” she does not believe it “excuses continuing destructive policies on new development coming in.”

“We can control that. Why on earth would we let that go in a way that it’s not the way it should be,” she said. “In this watershed, it is known to be destructive. It will have an immediate effect.”

Department of Planning and Zoning Director Valdis Lazdins in an email said the department takes “protecting environmental features seriously” and they “have established an in-house team to review and verify environmental features on property to be developed.” The do not rely solely on the information provided by applicants, he added. Receiving the exemption requires “detailed justification,” and in “any zoning district, achieving the maximum possible density is also not sufficient justification alone to allow disturbance.”

We “take our administrative review very seriously and require mitigation to offset potential impacts — we don't make these decisions lightly or arbitrarily,” he added.


The department recently allotted an exemption to the courthouse project where disturbing the stream buffer would allow builders to destroy existing pavement and restoring it to its “natural condition,” Lazdins noted.


Link, who was also a civilian engineer with the Army Corps of Engineers for 34 years, said there “certainly is an impact” when natural greenery is removed and not mitigated. He could not speak specifically to how DPZ’s exemption impacts the watershed as he does not know fully its application nor how often it occurs. Under Walsh’s passed legislation, the department is required to track and make public approved exemptions.

What is county the doing?

Howard County is now pursuing an “ambitious” flood plan that includes fully razing four buildings above the Tiber channel to widen streambeds and stimulate the flow of cascading waters. A tunnel will be bored on the north side of Main Street to divert water to the Patapsco River.

This estimated five-year plan will cost between $113 million and $140 million and includes demolishing the back portion of at least five buildings that sit above the Tiber channel. Officials say the projects will reduce future floodwaters, leaving an estimated maximum 3 feet of water on lower Main Street if the 2016 hits again.

A Howard County councilwoman has filed legislation to extend a development moratorium period in Ellicott City through October.

In addition to the flood reduction projects, officials plan to recommend lawmakers enact high stormwater management standards to reduce future floodwater. Born in the wake of the May 2018 flood, a moratorium was put into place to allow for additional studying and to halt development in the historic district through July 2019. Last month, legislation, which is poised to pass, was filed by Walsh to extend the period through October.

During a County Council meeting last week, officials suggested adding the 1,000-year storm event standard to its environmental site design management for new and redevelopment in the old Ellicott City watershed. Currently, 5% of land is being development and 1% is undeveloped.

Officials have identified at least 140 parcels in the floodplain that could potentially be used to create open space preservation areas. A specific cost or intention to purchase has not been developed fully, DeLuca said. Because former officials did not closely track stormwater drainage systems in the watershed, current officials are trying to locate them. They are not recommending changes to density or open space zoning.

The “perception” is that “it’s upstream development,” said DeLuca, that is causing flooding on land not near streams or rivers.

“We’re not saying one way or another whether it’s upstream development. But before we can make any kind of conclusion, let’s see how our infrastructure is performing. If our infrastructure is not performing correctly, then it’s contributing to the localized flooding in these areas … which … should not flood because they're not in a floodplain.”

Link could not speak specifically to the county’s flood reduction plan as he has not had time to review it. However, he did say he is “very impressed with the analysis and approach Howard County has done to get this point.” He specifically cited the 2016 report prepared by McCormick Taylor.

The report modeled a 100-year, heavy rainfall event for an “underdeveloped” version of the watershed. Engineers found that if Main Street was kept in tact and the watershed was changed to woods, lower Main Street would still see between 6 and 8 feet of water because of the town’s geological conditions. The model showed overwhelmed flood conveyance systems and oversaturated surfaces.

The same model was run against the watershed as is. The result was more than 8 feet of water on lower Main Street.

The problem is difficult to solve completely, said Link, who uses Ellicott City as an example for his students at the University of Maryland to study.

“It's hard to throw a band-aid on it and expect it to all hold on together,” he said. “There has to be a realization that there’s no way to totally reduce the water.”

The Berkowitzes are not coming back to Ellicott City. After selling their store to the county for $985,000, they moved their home and shop to Marriottsville in Carroll County. Their former building is among the four slated for demolition on lower Main Street.

The county has “to solve the problem,” said Lin Berkowitz. “We almost lost several tenants living in the building during the 2018 flood.”

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