Clean Water: Our Heritage, Our Legacy
Preventing Polluted Runoff
Airlie Gardens is a 67-acre public garden owned and operated by New Hanover County
since 1999. Its location on Bradley Creek, an ecologically and economically important
estuarine waterway, as well as the ten-acres of freshwater lake within the property, make
Airlie Gardens an ideal place to educate the public about preventing polluted runoff.
Airlie Gardens is in the Bradley Creek watershed.
New Hanover County is the second smallest county and the second most densely
populated county in N.C. The county is an urban, coastal county containing many
watersheds. Stormwater in our county drains directly to vital waterways like the Cape
Fear River, Intracoastal Waterway, and Atlantic Ocean via our watersheds. Whether you
live inland or on the coast, your actions impact our water bodies since everyone lives in a
watershed.
Sources and Issues
We categorize pollution into two categories: point source and non-point source. Point
source pollution comes from a specific source, like the effluent from an industrial plant,
and is regulated by the Government. Non-point source pollution, like agriculture, has a
wide range of sources and is the biggest source of pollution for our area. Our actions can
have positive and negative effects on pollution.
Stormwater runoff is rainfall that flows off driveways, parking lots, yards, and other hard,
impervious surfaces and heads to our waterways. Runoff picks up many different
pollutants along the way. Pollutants that reach our waterways include sediment, pet
waste, fertilizers, pesticides, yard waste, litter, and automobile fluids.
Today’s number one water quality problem in N.C. is sediment and the number one water
quality problem in New Hanover County is fecal coliform bacteria (found in pet waste).
Why is polluted runoff a problem?
Stormwater runoff nearly always has pollution levels that exceed health and coastal water
quality standards. Watershed pollution can make our coastal waters unsafe for swimming
and shellfishing. The health of aquatic life is also threatened because they start
accumulating toxins in their tissues. Besides being detrimental to the fish and the future
genes of its offspring, that same pollution inside fish tissues can also hurt humans when
we consume seafood. Toxins enter the food web from the bottom and embed themselves
in the tissues of organisms. As more complex life-forms prey on organisms with toxins,
the toxins become more concentrated in a process called biomagnification. The
biomagnification of toxins in complex organisms have detrimental effects on wildlife.
The brown pelican and the bald eagle, two important coastal birds, suffered from the
biomagnification effects of DDT runoff, and stared extinction in the face until efforts
were made to ban the use of that pesticide.
Solutions to polluted runoff: Best Management Practices (BMPs)
Stormwater BMPs help to improve water quality by slowing water flow, preventing
flooding, and removing pollutants and sediments from our waterways. Many BMPs
replicate natural systems to prevent and reduce polluted runoff.
Behavioral BMPs: picking up pet waste, not littering, washing your car on the
lawn, reducing the use of herbicides and pesticides, testing your soil to determine
appropriate fertilizer use, and composting your leaves and lawn clippings.
Structural BMPs: rain gardens, constructed wetlands, riparian buffers, shade
trees, oyster reefs, swales, bioretention areas, rain barrels, streambank restoration, and
habitat gardens.
Airlie Gardens has installed many effective BMPs to help prevent polluted runoff
at the Gardens. These BMPs include:
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Constructed Wetland
Rain Garden and Native Plantings
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Bioretention Area
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Vegetated Swales
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Rain Barrels
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Habitat Garden
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Riparian Buffer
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Shade Trees
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Oyster Reef
300’ Conservation Easement
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Pervious Pathways
How oysters help treat polluted runoff
Why are oysters important?
North Carolina’s native Eastern Oyster (Crassostrea virginica) is a valuable ecological
and economic resource for this region. Research has shown that our native oyster is a
keystone species in North Carolina’s estuarine environment, and the oysters are so valued
because of the three major functions they provide:
Filter: As filter-feeders oysters can filter between 25-50 gallons of water per day,
removing pollutants, sediment, and excess algae from the water, thus greatly improving
water quality. When oyster populations were at their peak, entire estuaries like the
Pamlico Sound could be filtered and cleaned in a matter of days.
Food: Oysters are vital components of the estuarine food web, and they support a
viable commercial and recreational fishery.
Fish Habitat: Oyster reefs provide habitat for many marine and estuarine species,
and many of the species living on oyster reefs help support commercial and recreational
fisheries. One healthy oyster reef can be home to more than an estimated 300 different
organisms including Southern Flounder, shrimp, clams and blue crabs.
How are the oysters doing?
Here on Bradley Creek, all oyster shellfisheries have been closed since the 1940s due to
widespread pollution and increasing human impact on the tidal creek ecosystem. Since
the early 1900’s, the N.C. oyster population has declined an estimated 90 percent due to a
variety of factors – oyster diseases, habitat loss, pollution, declining water quality, and
harvest pressure. However, over the past several years efforts to restore native oysters
have increased significantly and annual oyster harvests have also increased.
What can you do to save the oyster?
• Recycle your oyster shells – to find out how go to www.ncfisheries.net
• Protect oyster habitat by leaving creekside buffers or creating living shorelines if
adjacent to the water
• Use best management practices, like rain gardens, picking up pet waste, and
minimizing the use of lawn chemicals to reduce and clean stormwater runoff
before it enters our creeks
• Be a careful boater and avoid disturbing or anchoring in oyster reefs and
underwater grass beds
• Make sure you follow regulations on shellfish harvest
• Become an “oyster gardener” through the NC Division of Marine Fisheries and by
joining groups like the Citizens' Oyster Gardening Project
Action Opportunities
There are many agencies collaborating to help prevent and reduce polluted runoff. For
more information regarding preventing polluted runoff check out:
• The Environmental Protection Agency (hyperlink: www.epa.gov)
• The Environmental Education Fund (hyperlink: www.eefund.org)
• The North Carolina Association of Environmental Education Centers (hyperlink:
http://web.eenorthcarolina.org/net/org/info.aspx?s=101119.0.0.37430 )
• The Office of Environmental Education (hyperlink: www.eenorthcarolina.org)
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The North Carolina Coastal Federation (hyperlink: www.nccoast.org)
City of Wilmington’s Stormwater Services (hyperlink:
http://www.wilmingtonnc.gov/public_services/stormwater.aspx )
UNCW Center for Marine Science (hyperlink: www.uncw.edu/cmsr)
New Hanover Soil and Water Conservation District (hyperlink: www.nhswcd.org)
Bradley Creek and Hewletts Creeks Water Quality Recovery Program (hyperlink:
http://www.wilmingtonnc.gov/Portals/0/documents/Public%20Services/Stormwater/
G2B%20final%20plan%202012.pdf)
Acknowledgements
This project was funded under an EPA Section 319 Grant Administered by the
Environmental Education Fund, the NC Association of Environmental Education
Centers, and the DENR Office of Environmental Education.