U.S. Water News Online
NEW BERN, N.C. -- It's been five years since drastic new rules were established to reduce the flow of nitrogen into the Neuse River and scientists say the river is much cleaner as a result.
The state Environmental Management Commission adopted the rules to reduce the level of nitrogen from sewage and fertilizer after massive fish kills in 1990s.
The goal was to cut the levels 30 percent by this year in the 248-mile river that runs from Falls Lake north of Raleigh to Pamlico Sound. It serves as both a drinking water source and way to carry away treated wastewater from nearly 400 treatment plants.
Researchers identified nitrogen as the cause of an explosion of harmful algae blooms that use up dissolved oxygen and led to the fish kills.
The rules required sewage plant operators to control what they dumped into the river and forced farmers to control how much fertilizer ran off their fields into creeks and streams.
The rules also required developers to leave buffers along streams and creeks. Similar protections have since been put in place for the Tar-Pamlico River basin.
Ken Reckhow, director of the University of North Carolina Water Resources Research Institute, said there had been a downward trend in nitrogen concentrations in the river since 1997.
Reckhow said it was hard to pinpoint what caused the decline in nitrogen. Besides improvements in wastewater treatment plants and the buffers, there have been major hurricanes that flushed the river basin.
``They are all candidates, and they all may contribute,'' Reckhow said.
There are about 1 million acres of farmland in the river basin, where farmers in 17 counties report an average 37 percent reduction in nitrogen fertilizer. Subtracting the number of acres that went out of production, the reduction is about to 31 percent.
In some counties, including Wake, Orange, and Johnston, farmers reduced nitrogen use by more than 40 percent. Only two counties, Granville and Pitt, have not met the goal.
Farm nitrogen use may have decreased because of market demands that made farmers switch from corn to cotton, a crop that uses less nitrogen fertilizer.
``We must recognize that crop shift has played a role in reduction of nitrogen,'' said Natalie Jones, Neuse River Basin coordinator for the state Division of Soil and Water Conservation.
Despite the changes that have helped the river, there are constant challenges from rapid development along its route.
Some communities along the river such as Johnston County have tried innovative approaches to reduce nitrogen being dumped into the river, such as a piping treated wastewater to irrigate a golf course.
Ken York, the county's project coordinator, said rapid growth justified the $7 million cost of the project, paid for partly by a Clean Water Trust Fund grant.
JoAnn Burkholder, director of the Center for Applied Aquatic Ecology at N.C. State University, said drought contributed to apparent lower nitrogen levels because there wasn't as much runoff in the years 2000 through 2002.
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