Unexpected Findings

At this month’s Environmental Management Commission meeting, the NC Division of Water Resources provided an update on trends in animal production and its nitrogen and phosphorus waste byproducts as it relates to our state’s watersheds.

Water quality monitoring of the State’s Neuse and Tar-Pam watersheds has demonstrated nutrient pollution of these water bodies and resulted in their being listed as impaired. Meanwhile, the state’s efforts to curb pollution sources like waste water treatment plants and runoff from farms and development have not resulted in measurable improvement to the estuaries.  .

One belief was that increased animal waste is the source for nutrients preventing reductions in the overall nutrient loads flowing to the estuaries.  That belief is what led to the report to the commission.

What were the report’s findings? For the nutrient sensitive waters of the Neuse and Tar Pam, here are some results:

  • Between 2006 and 2014, plant available nitrogen (PAN) (i.e., nitrate (NO3), and ammonium, (NH4)) was estimated to have declined from 13 million lbs to 10 million lbs.
  • For the phosphorus (P205), levels dropped from 15 million to 11 million lbs.
  • Total poultry numbers stayed around 19.5 million birds from 1992 to 2006 and dropped to 16 million birds in 2014.

The report illustrates the complicated nature of nutrient management.  While the amount of animals and animal waste may be declining, monitored nutrient pollution flowing to the estuary shows little change. Its findings show that regulators need to broaden their scope to find solutions to the problem of nutrient pollution.

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