Living shorelines, wetland restoration, oyster reefs. Green infrastructure is an effective and proven method of increasing coastal resilience, stabilizing the shoreline and cleaning the waters in estuaries and the sounds of eastern North Carolina. But can the approach be used farther upstream in brackish water, in more urban settings to restore polluted waterways? The City of Jacksonville and local scientists are trying to answer that question.
“It’s a very different kind of setting, there are different stressors, there’s different physical structure there, but as best as we can tell, they seem to do quite well in these urban areas and that’s really promising.”
Today, the New River is teeming with life, but this wasn’t always the case. For more than four decades, the City of Jacksonville discharged treated wastewater effluent into Wilson Bay. And, in 1995, a dike collapsed at an Onslow County hog farm sending 25 million gallons of waste surging into the New River. Jacksonville’s Stormwater Manager Pat Donnovan-Pots.
“It made national news, the helicopters were flying over. And as it passed down the New River, it made very little impact because our river was in such bad shape. It was listed as one of the top worst on the eastern seaboard.”
She says levels of ammonia, phosphate and nitrates were off the charts. The fecal coliform counts were 35,000 to 70,000 per day.
“You’re only allowed 200 organisms per 100 mL of water for recreational waters. And like I said, we had 35,000 to 70,000.”
That’s when they knew something had to be done. The City eventually ceased discharging wastewater into the New River in 1998 with the completion of a land application wastewater treatment plant. The following year, a community based water quality improvement and habitat restoration effort began. Donnovan-Pots says they wanted to use natural habitat restoration practices, like oyster sills and wetlands to rehabilitate the contaminated waterway.
“To date, literally, to date, we’ve put in 8.1 million oysters and the reason why we used oysters is because one adult oyster, which is about the size of your hand, can filter up to ten gallons of water every 24 hours. So if you say 10 gallons times 8.1 million, that’s a lot of water turning over.”
Two oyster sills run parallel to the bulk head in front of Wilson Bay Estate Park. Six more surround Wilson Island. The City also installed three aeration units in the Bay to deliver oxygen to an anaerobic bottom.
“Before we had 0 mg/L of dissolved oxygen on the bottom and now we have the required 5 mg/L.”
They also constructed nine square acres of wetland and marsh habitat, which provide nutrient processing and fish nurseries. The restoration measures started to work right away and in 2001, Donnovan-Pots says they saw the bottom of Wilson Bay for the first time and found their first bottom dwelling creatures.
“I had never seen a crab pot, I had never seen a gill net or fishermen in this part of the river. And then after 2001 when we started putting out our report, some days there’s so many trout fishermen in the bay area, I actually have to dodge boats.”
Now that Wilson Bay supports a variety of aquatic life, it would seem that over the span of 17 years the waterway has fully recovered. But a team of local researchers with the University of North Carolina Wilmington, the Institute of Marine Sciences and the National Oceanic and Atmospheric Administration want quantifiable evidence of exactly how well the water quality and habitat restoration projects are working. Dr. Mike Piehler is a professor at the Institute of Marine Sciences in Morehead City. He’s also the Head of Estuarine Ecology and Human Health at the Coastal Studies Institute.
“What we were interested in is trying to make some fairly advanced measurements of nitrogen removal. Nutrients are really important in estuaries and when you have too much nutrients, that’s a problem. Salt marshes and oyster reefs, two of the things that the City of Jacksonville has been restoring, both of those habitats are known to be areas with elevated amounts of nitrogen removal.”
There are two sets of data being gathered. One component of the project involves taking sediment cores and water samples from wetlands in Wilson Bay to determine if they’re removing nitrogen from the water. Dr. Piehler is involved with collecting the mud samples and bringing them back to the lab.
“We set up incubations that allow us to understand the interaction between the sediment in the water and that interface is a really important area for nutrient cycling. And so we run our incubations and then at some point, our data will be in and we’ll have a sense of how effectively those system…how they are cycling nutrients and whether or not they’re effectively removing nutrients.”
Sediment and water samples from the restored wetland will be compared to samples collected from 20 acres of natural wetlands on the other side of Wilson Bay and areas without marshes. They’ll also compare current nutrient levels to those collected back in 1999.
The second component of the project examines the impact sea level rise has on wetlands in Wilson Bay. Marshes grow as water levels change. But if sea levels rise too quickly:
“They may not be able to keep up. And of course, we also see a lot of erosion.”
Research Ecologist at NOAA’s National Ocean Service Lab in Beaufort Caroyln Currin says work at the Wilson Bay site will allow them to track how salt marshes grow. The team of scientists recently installed six stainless steel rods 30 to 40 feet into the marsh and encased them in concrete.
“They provide a permanent point of reference from which measurements can be made to measure changes to measure both vertical and horizontal edge of the marsh. They require zero maintenance, and you just have a special instrument that you can bring out and set on top of that benchmark which can measure very fine scale changes in marsh surface elevation change on the orders of millimeters.”
While this type of study has been conducted at the coast, there isn’t much data for wetlands in brackish regions of the estuary, especially a restored area in an urban setting. Currin says it will take four to five years of data collection to get any real results.
The team of researchers are planning another trip to the site in the fall to collect more sediment core samples. NOAA will routinely monitor the sediment elevation table. In the Spring, the data and results of the project will be presented at the State of the River Address, held by the New River Roundtable. The annual meeting brings together environmental groups, educators, scientists, state, local and county government and Universities to discuss the health of the river. Jacksonville’s Stormwater Manager Pat Donnovan-Pots.
“One of the things about the New River, is that it starts and ends in the same county. We are cursed in that we can’t point our fingers up river and go it’s their fault. But we are also blessed that we can’t point our fingers up river and say it’s their fault. It’s our fault, and we are the ones that need to take ownership of it and be good stewards and continue to bring her back to life.”
And to make sure the New River remains healthy, the researchers involved with this project want to inspire the next generation. They’re collaborating with the non-profit Sturgeon City to provide educational material for K-12 students. The center will include demonstrations on the restoration of Wilson Bay and how the City continues to support other areas in need.