Third in a series on the Albemarle region’s environmental-economic connections.
Persistent algal blooms on the Chowan River are nothing new, but there was a time when the problem, one affecting public health, the environment and the coastal economy, got better. Then the blooms returned, and researchers are still trying to determine why.
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Blue-green algal blooms return each summer to rivers in northeastern North Carolina and linger. The North Carolina Department of Environmental Quality on July 18 issued a warning to avoid the Chowan River from Tyner on Indian Creek in northern Chowan County to Edenton.
Related: Lingering Chowan River algal bloom prompts state advisory
A 30-month program administered by the Albemarle Resource and Conservation Development Council is more than a year into looking at why the Chowan, Perquimans and Pasquotank rivers are so prone to the blue-green algal blooms that are caused by cyanobacteria feeding frenzies on nutrient-rich waters. These bacteria are potentially toxic to humans and animals and are associated with hypoxia, or deprivation of oxygen, in the water, leading to fish kills.
Albemarle Resource and Conservation Development Council Executive Director Elizabeth Bryant, a longtime resident of the Edenton area, said the problem is significant and real, and affects the area’s most important resources.
“With blue-green algal blooms in Edenton Bay and then farther north on the Chowan River,” Bryant said, “They’ve been severe to the point where warnings had to go out about people not swimming, that if they’re boating, they should steer clear of algal blooms. And not touch the fish in the area. Obviously, that restricts tourism.”
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The council serves 10 northeastern North Carolina counties: Camden, Chowan, Currituck, Dare, Gates, Hyde, Pasquotank, Perquimans, Tyrrell and Washington.
Bryant said the algal blooms can be breathtaking and affect towns across the region.
“If you get out of your car, and you can hardly breathe because of the scent of algal blooms, you’re going to get back in your car,” she said. “That will inhibit tourism to Edenton to Elizabeth City.”
Some of the region’s smaller towns’ economies depend on the summer travelers to or from the Outer Banks, Bryant added.
The 30-month-long study, Bryant noted, will yield data for the council’s entire service area. The grant requires gathering samples consistently throughout the year and, importantly, water samples are collected at tributaries and streams, and not necessarily the larger rivers.
The study is funded through the Environmental Enhancement Grant program administered by the state attorney general’s office. The program is part of a 25-year agreement that resulted from the state’s hog waste pollution case settlement with Smithfield Foods.
Attorney General Josh Stein, speaking at an event in May in Bertie County, said that in the 22 years since the agreement was signed, about 210 projects had been funded with awards totaling more than $40 million. Numerous awards have supported different strategies to improve water quality, Stein said.
Colleen Karl is the chairperson of the Chowan Edenton Environmental Group. She and others in the organization are among the numerous amateur, or public, scientists who are gathering samples for analysis as part of the program.
“It’s a very large watershed and we’re sampling on a lot of back roads,” she said.
The Chowan Edenton Environmental Group is sampling the waters of Potecasi Creek, a tributary of the Chowan River that joins the river at almost the same location as the Meherrin River.
“Some of those tributaries that come off Potecasi Creek, were earmarked as pretty high in nitrogen,” she said.
Nitrogen and phosphorous have long been known to contribute to cyanobacteria blooms, but other factors have also been identified, including those related to climate change.
Dr. Hans Paerl and Dr. Nathan Hall of the University of North Carolina Institute of Marine Sciences are analyzing the samples. Paerl, who has published papers on climate change and how it affects blue-green algae, explained that the organisms are influenced by changing weather patterns.
“These bloom organisms are particularly sensitive to climate change, including overall warming of the globe’s atmosphere and water, but then also more extreme events, like bigger storms and bigger droughts,” Paerl said. “Those things have come into the equation to more or less complicate factors in terms of coming up with recommending management strategies.”
Paerl has been studying the Chowan River watershed since the 1980s, when herring was still abundant in the river.
“When I first started working there, they had big herring pickling places (where) I used to buy my herring over in Colerain,” he recalled.
He was part of a team that came up with an early management plan for reducing the nutrient load entering the Chowan.
“When I first got hired to look at the blooms on the Chowan River, that was back in 1980, I believe. We did a good job. We identified both nitrogen and phosphorus and came up with some recommendations for how much reductions needed to take place in terms of input of those nutrients, and it proved to be pretty effective,” Paerl said.
It was a temporary reprieve.
“Then 15 or 20 years later, the blooms returned to the Chowan — pretty much the same players. So now we’re trying to figure out what has happened in the interim,” he said. “We’re still really aiming for nutrient reductions. We may need to reduce them even more now than we did before. The additional thing is climate change.”
But climate change does not completely explain why there has been an increase in algal blooms in rivers like the Chowan. As Hall explained, when the Albemarle Resource and Conservation Development Council first approached the researchers, they wanted to know where the nutrients had originated. In reviewing data and literature on nutrients in the rivers, a sudden spike wasn’t apparent.
“We have flow gauges (on the rivers) and the Division of Water Resources measures the concentrations. So, we have flow, we have concentrations, we can calculate loads,” Hall said. “Those major rivers don’t look particularly spectacular as far as how much load. The concentrations in the rivers really aren’t that high.”
What was apparent though was that relatively minor tributaries to the Albemarle Sound where gauges were in place or were otherwise monitored seemed to have significantly higher nutrient loads.
“For the few small streams where we do have concentration data, like the Scuppernong River, the Pasquotank River, the Perquimans River — these are smaller tributaries to the Albemarle Sound area — the concentrations are really high,” Hall said.
Those concentrations are also being found in the tributary streams — concentrations so high that they may be a significant contributing factor to algal blooms.
“A lot of the smaller streams are three times higher concentration than the big rivers. So if they’re carrying a proportional amount of flow and they’re about 15% of the watershed, they’re carrying three times higher concentration, they could be 40% of the load,” Hall said.
The study recently passed the 12-month mark, and there are still a number of unanswered questions. It remains unclear, for example, where or how the nitrogen is entering the river system.
“The organic nitrogen component is something that’s increasing in a lot of the streams in North Carolina. And it’s been kind of a head-scratcher as to where it’s coming from,” Hall said.
He explained that one of the goals of the project is to look across some of the streams that have different watershed and land-use characteristics, that are higher agriculture use, or include urban development, and try to investigate what the dissolved organic components look like.
Land use may be the key to mitigating extreme algal blooms, but to date the role of land use, how it affects nutrient loads, is not completely clear. To North Carolina State University researcher Dr. Chris Osburn, who is analyzing the data, the information is by no means definitive.
“Preliminary evidence points to changes in land use and climate (especially extreme rainfall events) that can mobilize DON (dissolved organic nitrogen) from wetlands and forested landscapes into tributaries, which could be driving some of the increases in DON observed in the Chowan River. Research into the sources of DON to these tributaries is ongoing,” Osburn responded to Coastal Review in an email.
Even if the sources of nutrients that are creating algal blooms in the Albemarle Basin are identified, Paerl said limiting the blooms is about the best that can be accomplished.
“We’re probably never going to be able to get rid of cyanobacteria in these slow-moving systems, and even in Albemarle Sound,” he said. “But we can keep it from getting worse.”
He said that’s essentially the point of mitigation strategies: holding back an issue or a problem from getting worse. “After all, cyanobacteria have been around on Earth for 2 billion years. They’re not going to go away.”
