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Could opening the Great Bridge Lock ease flooding in southern Virginia Beach? Or could creating an inlet?

The Great Bridge Lock in Chesapeake. [U.S. Army Corps of Engineeers]

Correction — An earlier version of this story did not fully identify City Manager Dave Hansen due to an editing mistake by John, who regrets the error.

BY JOHN-HENRY DOUCETTE 

VIRGINIA BEACH – The city has asked the U.S. Army Corps of Engineers to study whether changing operations at the Great Bridge Lock could help wind-driven flooding issues in southern Virginia Beach.

City Manager Dave Hansen wrote to the local branch of the U.S. Army Corps of Engineers in Norfolk on Sunday, June 30. His letter asks the corps to study “the feasibility and benefits of either keeping the locks open or removing the locks altogether” to reduce water levels. 

A theory is this — adjusting or removing the locks might change water levels in the North Landing River and Back Bay, though significant examination would be needed to determine whether such a step would help. At first blush, some officials noted, the returns might be small. 

This and another idea that has been informally discussed — to essentially create an inlet or way for sea water to wash into the bay somewhere south of Sandbridge — show how locals and some are looking at a range of ideas to help address wind tide-driven flooding.

Officials stressed that conditions in the southern watershed of Virginia Beach are complex and probably will require a variety of efforts to address challenges such as sea level rise and flooding due to southerly winds.

Virginia Beach is engaged in a wider look at flooding issues throughout the city, which includes mapping its watersheds.

Conditions of the southern watershed, where wind tide flooding is a concern surrounding the bay and connected waterways, are different than flooding issues elsewhere in the city. Among other concerns, a recent presentation by a city consultant indicated that the southern watershed will be especially susceptible to sea level rise. 

Regarding the locks, Deputy City Manager Tom Leahy said there are a number of questions, including looking at the distance of the locks from Virginia Beach waters in the city’s south, the capacity of the canal, and whether possible returns on any change to operations are worthwhile. Potential effects upon other bodies of water must be considered, too.

“The corps is going to look at it,” said Leahy, who was among the city officials to have a recent initial conversation with the corps about the idea. “It could have some extremely minor effects in the North Landing River.” The possibility it would have an impact on Back Bay is more remote, he said.

An informally-discussed idea to create an inlet would be a far more complex one to tackle, he added. There has been no formal request to study that idea.

Hansen’s letter about the locks came after a May discussion between state Del. Barry Knight, R-81st District, and Greg Steele, chief of the water resources division for the U.S. Army Corps of Engineers Norfolk District. Knight said Al Henley, who has served on the planning commission, was at the meeting, too.

Steele said the corps may be able to conduct an analysis, perhaps within a year, looking at the system and issues such as the development in the area. He said the meeting with Knight covered operations of the locks and how they are meant to avoid dangerous conditions in the canal, as well as preventing waters from the Elizabeth River from causing salinity issues in other bodies. Initial study might cost $150,000.

Steele, too, was cautious about whether any change with the locks could have the outcome some desire. He said “more often than not” high water is on the Chesapeake side when the locks are closed. 

“It’s actually keeping high water from going down to Virginia Beach in certain high water and storm events,” Steele said.

Susan Conner, chief of the planning and policy branch for the Norfolk district, said study might lead to other ideas to address issues that Virginia Beach faces, even if its results did not support changing locks operations. 

“The benefit is there are questions out there, and we could investigate those,” Conner said.

Wind tides impact southern Virginia Beach when there are strong southerly winds. They might be mitigated by increased salinity in the Back Bay watershed, which might encourage the growth of aquatic grasses, according to City Councilmember Barbara Henley, who represents the Princess Anne District. Henley’s husband and Al Henley are cousins.

Barbara Henley said aquatic grasses have helped stabilize waters in the bay. Manmade dunes may be contributing to the severity of flooding from wind tides in the area.

Informal discussion of creating an experimental breach in the dune line could allow some saltwater from the ocean to penetrate Back Bay and its tributaries. In the past, ocean water has been pumped into the bay.

An idea of a making such a cut was suggested by local farmer Steve Barnes. 

Steele said the idea for a cut would be a complex one to investigate. If a change was suggested for federal land at the wildlife refuge, for example, there would be a great deal of environmental study that would need to involve the U.S. Fish and Wildlife Service.

A 1951 study prepared by Harold Waterfield, then the former chief engineer for the corps’ Norfolk District, traced some flooding problems back to the a couple of potential causes. The Independent News reviewed a copy of Waterfield’s paper. It did not reflect a formal opinion by the corps but recommendations by the author. 

Waterfield wrote that sand fences dammed out seawater, affecting the bay. Also, he wrote that restoration of the locks in the 1930s following a period of disuse suggesting “water levels may have been reduced” during the period in which the locks were not used.

“The farmers said when they did not have any locks, they did not have flooding,” Knight said during an interview.

“Mother nature knows best,” he added. “I think it’s a wonderful idea.”

Waterfield’s report and a 1980s study of Back Bay noted that certain levels of salinity may positively encourage vegetation in the bay. When aquatic grasses died, wind and water action, which were slowed by thick vegetation, seemed to have increased. 

“The natural environment was disrupted,” Henley said. “I just think that all of this information deserves real consideration.”

However, Henley said results of city studies of the entire watershed and efforts to map the area are important before any specific actions are considered. 

“I think there’s a combination of issues, and we need to look at the broad picture,” Henley said, noting that the city is doing so by studying the southern watershed. “I think it will probably take a number of things.”

Waterfield’s paper discussed the effect of higher water levels, particularly in summer months, damaging crops decades ago. He linked higher water levels in the bay to a combination of manmade barriers and closing the locks, which have “materially damaged the farmers, ruined the aquatic vegetation and consequently greatly affected fish and wildfowl adversely.”

Storm water management and resiliency are priorities citywide, including in the southern watershed, said Greg Johnson, the city’s storm water technical services engineer.

The situation here is particularly challenging because much of the land on the Back Bay watershed has elevations only a few feet above sea level, he said, and water quality as well as quantity must be part of the consideration of any approaches. 

Regarding the Waterfield paper, he also noted that a modern scientist studying grass conditions in the bay using current data could draw different conclusions.

The city is working with the corps, Leahy noted, and will ask a consultant studying city watersheds for data to help address questions about some of the ideas under discussion. 

Again, those studies need to take place before investing in any major decision.

“You have to do the engineering,” he said. 


This story includes reporting by contributor Jane Bloodworth Rowe.


© 2017 Pungo Publishing Co., LLC

The Independent News

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