Learning from an old sewage plant
STURGEON CITY, N.C. — It’s another day of learning at Sturgeon City, an environmental education center on Wilson Bay in Jacksonville. Students on a field trip to the center surround Director Paula Farnell as she peers into a microscope. A drop of water from the bay sits on the slide beneath the microscope. Farnell tells students what to look for.
“You’ll probably find some plant matter in there or at least some stuff moving around,” Farnell tells the group. “There’s a lot to see in a tiny drop of water.”
It’s a unique setting for a field trip. The entire education center is housed in an old sewage treatment plant on the shore of the lake. Farnell explains the reason for that.
“The idea was bring life back to the bay and utilize this closed down plant to learn from our past mistakes and educate this next generation so they don’t make those same mistakes,” says Farnell. And there are a lot of mistakes to learn about.
Overwhelmed sewage plant polluted nearby bay
The sewage treatment facility was built at the same time as Camp Lejeune and the related military facilities around the Marine Corps base. However through the years the population around the base and in Jacksonville boomed. But the city never expanded the plant’s capacity. Eventually, the facility was overwhelmed. The effluent wasn’t treated properly and was discharged directly into the bay. The sewage and other pollution killed the bay.
By the 1980s and 1990s, Wilson Bay was a toxic and essentially dead body of water. Bacteria counts were so high that fishing and swimming were prohibited.
“You’re allowed 200 organisms per 100 milliliters of water, and we had 35,000 to 70,000,” says Pat Donovan-Potts, a marine biologist and storm water manager for the City of Jacksonville. “The lake looked bad, it smelled and you had to immediately wash if you got any water on you. So it was closed to recreational and commercial uses.”
The city makes changes
Public pressure and federal environmental laws forced the city to act.
“You had a council that when pressed to this said it is our moral obligation to clean up Wilson Bay,” explains Glenn Hargett, assistant city manager with the City of Jacksonville. The city made a major commitment of time, money and resources. A new wastewater treatment plant was built and natural habitats were restored.
Wilson Bay becomes a living laboratory
Stand on the shoreline of Wilson Bay today and you can see fish swimming in the shallow water. It has taken years, but Wilson Bay is alive again. It’s also a living laboratory for effective environmental restoration. Which is why Kathleen Onorevole, a research technician with the University of North Carolina Institute of Marine Sciences is on a boat in the middle of the lake collecting mud samples from the lake bottom.
“A lot of times restoration projects will happen and people will spend a lot of time and money and effort like here in Wilson Bay, and there’s not the opportunity to go back and figure out what worked,” Onorevole says as she pulled a tube full of wet mud onto the boat. “This is a great opportunity to find out what went well and what restoration goals have been met."
Studying how bacteria and oysters clean the bay
Those icky, slimy mud samples will be brought to laboratories so researchers can measure the microbial processes that are happening in the lake and marsh environments. Scientists want to know how the microbes living in and around the oyster reefs and the salt marshes are removing nitrogen from those systems. That’s because nitrogen has an impact on algae populations.
The microbes and other creatures that researchers find living in the mud are an indication of how effective natural ecosystems restore Wilson Bay. Oysters clean the water and oyster reefs provide habitat for microbes that remove excess nitrogen. Nitrogen is delivered through storm water runoff and too much nitrogen leads to rapid algae growth, which makes for poor water quality.
“We are finding that the restored marsh is very effective at removing excess nitrogen,” says Onorevole, as she places a cap on another mud sample and labels the location it was collected.
The boat is near one of the new marshes that was built on the edge of the bay. “While all of the habitats are removing nitrogen the restored marsh is able to remove it faster. “That’s good news, because it shows that the new habitats that were created as part of the restoration project are continuing to restore and maintain the water quality in Wilson Bay.
Is the shoreline receding?
Scientists are also studying whether the shoreline around Wilson Bay is growing or receding. Researchers have installed the base for an instrument called a surface elevation table at several points around the bay. A pole is inserted into an aluminum base that has been driven into the ground. The pole has a plate at the top where researchers attach a cross bar. The bar is balanced, then thin plastic rods are inserted through the cross bar until the bottom of the rod rests on the marsh surface.
Once all of the rods are installed, it’s easy to see how uneven the marsh surface is. That’s because the tops of the poles are uneven. But that’s the point, because those differences can be measured.
“We measure the distance between the top of the cross bar and the top of the rod and we can measure the changes to millimeter accuracy,” explains Carolyn Currin, a researcher with the National Oceanic and Atmospheric Administration. “Over time we’ll have multiple measures, because we rotate the poll and that gives us the changes in marsh surface in a roughly square meter area.”
And by taking those measurements at the same point, several times per year, researchers will know whether the marsh surface is growing or receding. That’s important because marshes provide habitat for a variety of animals and birds. Marshes are also important for preventing shoreline erosion.
“The change in surface elevation is due to two processes,” says Currin. “One is the trapping of sediments and building from above such as when the area floods from a storm. The other is below ground root production and building from below. If the marsh is healthy and things are growing, the surface will grow as vegetation dies and decays but it will also grow from root matter.“
Funding from North Carolina Sea Grant
North Carolina Sea Grant is funding the Wilson Bay research. The findings will help guide more coastal restoration work.
“This marsh system is a good example of why we want good healthy coastal ecosystems,” says Jennifer Dorton, with North Carolina Sea Grant. “We want to make sure they are keeping up with sea level rise, but we also want to make sure they are providing services like protecting infrastructure behind these houses. And of course, marshes are a crucial habitat for a lot of species.”