Flooding: Back Bay marsh restoration a focus among southern Virginia Beach projects in referendum

BY SANDI SNIDER AND JOHN-HENRY DOUCETTE

COURTHOUSE— City voters are considering whether to support a sweeping $567.5 million bond referendum that would speed up key projects meant to fight flooding, and a series of meetings have included a focus on efforts in southern Virginia Beach – including one that could help restore aquatic vegetation that has been in decline in Back Bay.

On Wednesday, Sept. 1, Councilmember Barbara Henley hosted a meeting at the Senior Resource Center, Inc., to follow up on focus group discussions that took place in 2019 about the Back Bay area’s ongoing hazards due to wind-driven flooding.

Following public input, the city tasked Dewberry Engineers, Inc., to study ways to reduce the impact of flooding in and around the bay. Last month at the Senior Resource Center, Dewberry’s Alaurah Moss and Brian Batten gave a presentation about assessment of flood-reduction strategies that resulted from the community conversations. The strategies were the creation of an artificial inlet that could discharge water from the bay during wind-tide flooding, an inverted siphon system to move water from the bay into the ocean, a pumping facility that would discharge water from the bay into the ocean, and a marsh restoration plan. 

According to the summary of the projects, three of the plans would require significant construction that would possibly cause environmental impact. 

The artificial inlet would need to be built at Little Island in Sandbridge and the cost could be prohibitive. The inverted siphon option would be less costly, but also has many production obstacles. And the pump facility would also need to be constructed at Little Island, and it would affect two acres of marshland to construct.

The marsh restoration option has scored the most positives of the alternatives and has the lowest impact on the environment, according to the presentation – and $40 million in “green infrastructure” solutions, including marsh restoration in Back Bay, would be part of what is funded if the flood mitigation bond referendum passes.

The objective of the marsh terrace project is to build back the marshlands that have been lost to slow down the water flow naturally, as a more robust population of aquatic vegetation did in the bay in the past, thus helping to prevent extreme flooding. 

“The goal is to make it come up a lot slower,” Henley said on Thursday, Sept. 23. “Right now, without the marshes or anything there, that’s why it comes up so fast.”

Slowing it down can give the area time for the wind to shift, she said, which is how water gets out of the bay.

“This pilot project will allow us to see if it works,” Henley said, “and, if it does work, then we can do more. I think we’ve got about 2,000 acres to replace in Back Bay. This is 200.”

This marsh restoration plan is part of the overall city policy to address sea level rise and flooding concerns, and the marsh terrace pilot program is now underway to try to restore some of the lost vegetation in the bay. This project is slated to add 260 acres of marshland by building marsh terraces in the bay. In addition to slowing waters driven into the bay by winds blowing from the south, returning marsh grasses will provide habitat for wildlife and improve water quality, according to the city.

Preliminary studies have been done with the help of scientists from Virginia Tech, and a similar plan was successfully initiated in the Gulf of Mexico. A matching grant has been approved by the federal government to help fund this project which will help to fast-track the process.

Utterback discussed differences in flooding concerns in the southern watershed area during the meeting and where these projects fit in.

“The idea in the southern rivers watershed is to use natural mitigations to slow the water down and couple that with engineered defenses to hold the water back,” Utterback said.

“We evaluated different opportunities for a marsh restoration project,” she said. “We wanted a location that had the greatest potential to provide flood reduction and habitat restoration benefits.”

The marsh restoration project is within Back Bay National Wildlife Refuge in an area that has been undergoing “significant degradation,” meaning losses of vegetation and habitat. Over the last century, about 2,000 acres of vegetated marsh habitat have eroded in Back Bay and is now open water, she said, and much of the of submerged aquatic vegetation has been lost.

“Without the vegetation, there’s no resistance to slow the water down,” she said.

Modeling by the city anticipates thousands of additional acres of marsh could be lost without action. The project means to make the bay more resilient by adding back marsh island habitats and stabilizing what is there.

“The primary goal of the marsh restoration project is to add resiliency in Back Bay by restoring and creating new marsh island habitat,” Utterback said.

Visit www.vbgov.com/rippleeffect for details about each of the projects, and attend one of the upcoming community meetings either virtually or in person to learn more and have your questions answered.

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