Making Waves:
Report Examines Impacts and Solutions for Shoreline Erosion

July 13, 2017
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July 31, 2017

By Virginia Sea Grant Science Writing Intern Sarah Ruiz

On summer afternoons recreational boats slice through the waters of the Chesapeake Bay, leaving behind only their wakes. Although boat wakes may seem inconsequential in the grand scale of the bay, the ripples they generate join the rhythm of the natural waves that lap against the shore, increasing their intensity. With that increase in energy, may come an increase in the rate and severity of shoreline erosion.

In order to explore both the potential impacts of boat wake erosion on shoreline habitats, as well as possible policy options to manage those impacts, the Scientific and Technical Advisory Committee of the Chesapeake Bay Program commissioned a comprehensive report. The result, published this May, was a collaborative effort between scientists at the Virginia Institute of Marine Science (VIMS) and policy experts at the Virginia Coastal Policy Center (VCPC) and included authors from The Chesapeake Bay Trust, the National Oceanic and Atmospheric Administration (NOAA) and Old Dominion University.

The science section of the report focused largely on investigating the association between boat wakes and increased shoreline erosion.

According to Pamela Mason, Senior Coastal Management Scientist at VIMS and one of the authors on the report, this association is one that largely hasn’t been scientifically explored.

“There isn’t that much in the scientific or peer reviewed or gray literature,” Mason says. “There are some studies that are sort of few and far between, and so it was up to us to drill down and look for that information.”

To collect this information, scientists at VIMS conducted a review of the available literature, as well as analyzed the data from several monitoring stations around the Bay. In order to determine if recreational boating was significantly impacting erosion scientists examined turbidity, a measure of the cloudiness of the water which indicates suspended sediments in the water column.

“We looked for signatures to see if, in times that we would have expected high boat usage, like on the weekends, that there would be an uptick in the sediment that was observed,” Mason says.

The report did find these increases in turbidity, indicating an association between boat activity and erosion, but noted that there wasn’t enough data currently available to provide any precise quantitative information on just how much boat wakes were actually contributing to erosion.

“We have not really as a scientific community gone out and looked for that effect,” Mason says. “One of the recommendations of the report is to make a stronger effort to monitor for some of those changes, and to look if we can develop some numbers, and see just how much shoreline erosion can be attributed to boat wakes.”

Despite the gaps in data, the report still notes that actions should be taken to mitigate boat wake impacts because initial indications are that wake action does negatively impact shorelines. One of the most feasible options for mitigation would be to instigate no-wake zones, especially in shallower and narrower water bodies where the wakes have less room to dissipate before hitting the shore.

 

Video: Daniel Diaz-Etchevehere

The Virginia Coastal Policy Center partnered on the report in order to address the question of possible policy options for minimizing the potential harmful effects of boat wakes. The research was assigned to students at the William and Mary Law School, who examined the legal framework for no-wake zone policies in Virginia, Delaware, and Maryland, and compared these policies to other shallow water estuaries across the United States.

According to Angela King, Assistant Director of the VCPC, one major finding of the report was that the policies are not uniform across the Chesapeake Bay, which could hamper attempts at tackling this problem. The VCPC found that each of the bay states have their own avenues for implementing boat wake restriction policies.

“You could really benefit from having a uniform policy for the shorelines in the bay,” King adds. To address this, she suggests connecting experts and policy makers across the Bay to discuss options.

“One way that has been suggested that those policy options could come to light would be to empanel a group of experts from the Bay states to discuss the issue, discuss the policy options, and come to an agreement that could be implemented bay-wide,” King notes.

Implementing boat wake restriction policies would effectively mean placing a speed limit on recreational boaters, potentially impacting their travel time through certain waterways. A failure to effectively manage erosion, however, could mean waving goodbye to Virginia’s shorelines, and the unique habitats and ecosystems they support.

Although this report was only able to make recommendations for future policy actions, Mason said she is glad the first steps are being taken to protect the Chesapeake’s shores.

“It’s hard to manage for something when you don’t understand the story,” she says. “This report moves us much further along that path.”

To read the full report click here.

Takeaways

• Report combined science expertise and policy recommendations
• There is an association between boat activity, and increased shoreline erosion
• There is not enough data to quantitatively measure the precise impact of boat wakes
• The bay would benefit from a uniform policy on boat wake restrictions

Below: Oystermen depart for early morning haul. Credit: VASG/Dennis Quigley
"It’s hard to manage for something when you don’t understand the story." Pamela Mason
Despite the gaps in data, the report still notes that actions should be taken to mitigate boat wake impacts because initial indications are that wake action does negatively impact shorelines.
 

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