Feb. 16, 2001 Chapel Hill -- Mayflies, dragonflies, stone flies and caddis flies can't take the witness stand in court, of course, but they can provide strong evidence of how well or badly construction workers follow sediment pollution prevention rules, a unique new environmental study shows.
The giant "disturbance" study, conducted by University of North Carolina at Chapel Hill scientists, revealed that builders appear to follow regulations in direct proportion to how well they are policed. If enforcement is slack, chiefly because of too few inspectors, many builders take short cuts that damage water quality. If enforcement is strict and backed by meaningful penalties, they will conform to the rules.
What are needed, the UNC-CH scientists conclude, are enough state and county staffers to ensure that rivers and streams are protected. Among the consequences of not adequately curbing sedimentation are fewer healthy fish, less native seafood and poorer functioning streams.
Drs. Seth R. Reice, associate professor of biology, and Richard Andrews, professor of environmental sciences and engineering at the UNC-CH School of Public Health, directed the research and released results Tuesday (2/13/01). The U.S. Environmental Protection Agency and National Science Foundation supported the project with a four-year, $577,000 grant through their Science to Achieve Results (STAR) program.
Researchers monitored benthic macroinvertebrates -- insects and other critters living near and on the bottoms of 17 state waterways -- upstream, downstream and adjacent to construction sites in the N.C. Piedmont. They focused on Orange County, Wake County and the 16-county central Piedmont area known as District Four of the N.C. Division of Land Quality. District Four covers 8,000 square miles.
"Our principal task was to try to understand what made for effective control of sediments from construction sites, and to that end, we also interviewed contractors, developers and both erosion and sediment control administrators and site inspectors," Reice said.
They also studied fish populations and measured water quality and leaf decomposition rates at work sites before, during and after construction. They sampled especially heavily following rainfalls of at least a half inch that could wash sediments from disturbed areas. Later, the team evaluated the streams after construction was completed and vegetation partially restored.
"As you can imagine, this was a very complicated, detailed study during which we sampled and identified more than 300,000 invertebrates," Reice said. "Dr. Andrews and Ph.D. student Joanne Carmin, now on the Virginia Tech faculty, coordinated and conducted another side of the study, which was a public policy analysis. That means ours was the first investigation ever to look at the actual impact of developers and regulators on natural stream ecology in this way."
Orange County had strong sedimentation rules and strong enforcement, while Wake County had weaker rules and strong enforcement, he said. District Four had the same rules as Wake County, but weaker enforcement because only four full-time inspectors were available to monitor 2,000 construction sites during the period studied from 1996 to 2000.
As expected, extensive laboratory work and data analyses showed better water quality in Orange County than in Wake and better water quality in Wake than in other District Four counties. Because their workloads were more reasonable, inspectors in Orange and Wake could be more vigilant and were tougher on developers, sometimes issuing stop-work orders.
"The problem for District Four is that inspectors, who are good people doing their best, can't possibly keep up there, and it's likely they can't visit a construction site more than once before it's completed," the ecologist said. "The bottom line is that problems lie not with the counties or where the streams are but with enforcement, which is just not good enough in most counties." Rules to prevent erosion go into effect in Orange County whenever a half acre or more of land is disturbed by construction. The overall state standard kicks in when an acre falls under construction. The N.C. rules ought to be tightened and better enforced, the biologist said, but they still are better than comparable regulations in all other states.
"Just this year, sediment violation fines went from $500 a day in North Carolina, which were a joke, to $5,000 a day, which can get developers' attention by pinching them," Reice said. "Our data provide a powerful argument for hiring many more sedimentation inspectors for North Carolina." In the past two years, a proposal to hire 120 new inspectors went through the state budget process, he said. That number kept being whittled down at various stages and finally ended up as zero. "Because the rate of construction has increased fantastically here, we've got a real problem now," the biologist said. "Streams can be thought of as the digestive tracts of forests. If we kill off aquatic insects, we're going to lose fish populations, and fishing in this state will be severely impacted."
- Healthy streams perform vital ecosystem services for people. They break down organic matter, their plants fix solar energy, they recycle nutrients, recharge groundwater and perform numerous other important functions, he said. The best way to control erosion during construction is to dig and maintain sedimentation ponds that trap water and prevent it from running downhill into streams.
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