December 7, 2017
Rising Sea Levels Complicate Flooding Issues
By CATHERINE KOZAK
Coastal Review Online
and angst over extreme flooding after Hurricane Matthew on the Outer
Banks echoed the outrage over ponding water here expressed more than a
decade ago, but now local governments are actively working to mitigate
the problem. At the same time, rising seas and record rainfalls have
made solutions more challenging and costly.
The towns of Manteo and Nags Head, for instance, provide telling
examples of the complexity – and urgency – involved in managing storm
drainage on North Carolina’s low-lying barrier islands.
“I would say it’s gotten more challenging because when you look at
these rain events, the frequency and amount is greater,” said Andy
Garman, Nags Head deputy town manager.
Rainfall has become more intense and localized, he said, randomly
overwhelming different sides of town with stormwater. And there’s just
more rain overall. In 1979, the annual average rainfall in the town was
45 inches a year; it’s currently about 60 inches a year. Between
October 2015 and October 2016, 70 inches of rain fell. In July 2017, 4
inches of rain was dumped within an hour across a 1-mile area.
Drainage is a problem all over the Outer Banks, a resort destination
known for its beautiful beaches. It is also one of the most vulnerable
areas on the U.S. coast to the effects of sea level rise. Although
higher groundwater levels and increased beach erosion have been issues
for years, the relationship between development and stormwater
management had been resisted – until it could no longer be ignored.
Back in August 2004, then-state Sen. Marc Basnight, responding to a
public outcry, called an informal meeting with citizens on the northern
Outer Banks to talk about flooding that had resulted from a series of
tropical storms. People were livid about huge puddles standing for
weeks in their yards and on roads and were demanding action. Basnight
said that he wanted to spur discussion about solving the increasing
drainage problems on barrier islands while protecting water quality.
In retrospect, that meeting, which also included representatives of
numerous state agencies and local officials, may have indeed galvanized
the community to start to address stormwater management in a
“I would caution us that we don’t study something to death for five or
10 years,” then-Dare County Board of Commissioners Chairman Warren
Judge told the overflow crowd that filled Kitty Hawk Town Hall. “It’s
time to act. The incidences we have had during (hurricanes) Alex,
Bonnie and Charley, we all have to agree, are unacceptable.”
With Basnight’s support, the Outer Banks Hydrology Committee was formed
to tackle the problem. Members included, among others, representatives
from Dare and Currituck counties and northern Dare towns; the North
Carolina Division of Water Quality; the North Carolina Division of
Environmental Health; the North Carolina Department of Transportation;
the North Carolina Homebuilders and Realtors associations; and the
North Carolina Coastal Federation.
After holding 11 meetings and listening to 15 different experts speak
on a range of topics, the committee concluded in its November 2005
findings report that “the Outer Banks water budget is grossly out of
balance” and that “water resource management on the Outer Banks needs …
a holistic approach addressing the entire hydrologic water budget and
working across government and agency jurisdictions.
“The committee agreed that we cannot ‘restore’ the hydrology of the
Outer Banks,” the report said, “but we need to reconstruct and manage
the system in a manner that we hope will ‘do no harm.’”
Thirteen years later, every municipality in Dare County, as well as the
county, has implemented more stormwater management rules and practices.
Even though the terminology used in planning is mostly centered on
flooding causes – ocean overwash, sound tide and heavy rainfall – it is
clear that environmental conditions are changing faster than local
governments can keep up.
“The town had done a stormwater master plan in ’06 with a consultant,”
Garman said. “And it resulted in a list of projects, a lot of which
Work had continued on the plan, he said, but flooding from Matthew
prompted Nags Head to pick up the pace. An inventory of drainage
structures in the town had been done from Jockey’s Ridge south, Garman
said, and the northern end – last surveyed in 1982 – was just completed
in the spring.
“That’s really the first step,” he said.
Invasive alligator weed that clogs drains and ponds requires treatment
and removal, and storm-driven debris has to be cleared out of ditches
to prevent flooded yards and streets in Nags Head. Frequent and heavy
rainfall raised groundwater levels and leaves the land saturated,
allowing water to pool in low areas. During Matthew, one area on the
Beach Road had 3½ feet of water.
After prolonged flooding from rains this summer, more than 20 Nags Head
residents held an impromptu meeting in September to demand better
management of drainage, and it was a prominent issue in recent town
Dave Ryan, town engineer for Nags Head, said that the town’s dedicated
stormwater tax of one penny generates $235,000 a year, but it’s not
adequate to address all the stormwater management needs, despite the
fee being increased over the years. The town recently created a
stormwater committee to help prioritize maintenance and capital
“It’s an ongoing effort,” Ryan said.
Long-term solutions could include groundwater manipulation, which uses
perforated pipes and a pumping system to artificially lower the water
table. But the remedy, which proved effective at the Whalehead
subdivision in Corolla, is estimated at $8.5 million and would face
regulatory challenges on discharge into Roanoke Sound.
The town has long had a voluntary “septic health initiative” to help
maintain water quality, but higher groundwater could eventually
compromise some of the systems.
“Over time,” Garman said, “I think there’s recognition that we’re going to have monitor water quality.”
Nags Head had worked with North Carolina Sea Grant in gathering public
feedback to establish sea level rise adaptation goals, which are
included in the FOCUS Nags Head plan adopted this summer.
When discussions were held in 2015, stormwater issues did not factor
strongly, said Jessica Whitehead, Coastal Communities Hazards
Adaptation specialist for Sea Grant.
Although it has since become more evident that climate change and
rising sea levels influence flooding, answering how to address
stormwater issues in that context is another story.
“That’s something we haven’t figured out yet,” Whitehead said.
Away from the ocean over in Manteo, the town has somewhat different
challenges with stormwater management that over the years has been
hampered by outmoded drainage systems, half of which were installed on
private property, and waterfront businesses situated inches above
adjacent Shallowbag Bay.
“With anything we do, we’re fighting gravity,” said town manager Kermit
Skinner. Drainage outflow into the bay has to be regularly cleared of
solids to prevent water from backing up into the streets.
In a partnership with the town, North Carolina State University, North
Carolina Department of Transportation, the North Carolina Clean Water
Management Trust Fund, the Outer Banks Visitors Bureau and the Coastal
Federation built a small, man-made saltwater wetland on the corner of
Grenville Street and U.S. 64 in Manteo to create a model stormwater
By holding the storm discharge in the saltwater wetland for 72 hours
before it slowly drains into the soil, pollution can be decreased,
explained Michelle Clower, coastal specialist in the federation’s
A recent report on the experimental project found a significant
decrease in bacteria levels, she said, although more study is required
to determine the role of salt in the die-off.
“I can confidently say it is working well,” Clower said.
For about six years, Skinner said, Manteo has had a 2-cent tax for a
dedicated stormwater fund. So far, the town has spent about $2 million
for an engineered stormwater conveyance system, which included moving
infrastructure off private property and major improvements of drainage
lines under several streets. Additional improvements are underway or
planned on other roads.
“We have historically had issues with tidal flooding,” Skinner said,
adding that it has become more extreme. “Anyone who doesn’t think the
seas are rising hasn’t had their eyes open.”
Skinner said that with the drainage improvements, sound tide has been
able to drain more quickly. But he does not pretend that there are easy
solutions to downtown flooding in coming years.
“We’re fighting a rising tide, and that is going to be a tremendous
challenge,” he said. “There’s no doubt in my mind – it is markedly
worse than it used to be.”
And this summer’s hurricanes and rain deluges indicate that things are
not going to get any better. According to the 2005 hydrology report, to
fix the problem without harming water quality would take a long-term
commitment to integrate jurisdictional responsibilities and seek
flexible solutions “to sustain both the human and environmental
“There is no single magic bullet to solve the stormwater and flooding
problems,” the report said. “The causative factors for the problems on
the Outer Banks in the summer of 2004 were generated incrementally with
changes in land use associated with the development process.”
Or in other words, there’s less soil and vegetation to absorb water and there’s more impermeable ground cover.
“We have to acknowledge that it’s a mess that we made by not regulating
development sufficiently,” then-Manteo Mayor John Wilson said in 2004
at Basnight’s meeting. “We have to look at our future development.”
But in 2017, there’s a lot more water.