This past week, NC’s Water Resources Research Institute held their annual meeting. I dropped in for a session and talked with some presenters. One theme presented in several talks is the continued and expanding problem of excess nutrients, or eutrophication, in area waters and the challenges that this presents.
Glenn Dunn touched on nutrient reductions efforts in the Neuse. In the late 1990’s, NC passed a set of rules for this watershed to reduce its nitrogen levels by 30% from 1991-1995 levels. In response, waste treatment plants upgraded their treatment technology. Monitoring of their discharges has shown decreases of over 60% on their annual nitrogen loadings. Analysis of the estuary, however, does not show significant change to the estuary when flow is accounted for. Why? Other sources of nitrogen are offseting their reductions.
Examined by Lebo, Paerl, and Peierls in research released in 2012, several forms of nitrogen are shown to be decreasing (see the graph below). TKN, or organic nitrogen, however, has actually risen since the 1990’s when the estuary saw troubling algal blooms and fish kills. Their analysis shows that the Neuse estuary and its ecosystems continue to be threatened by excess nutrient levels.
I’ll post more soon on the expanding areas of the state facing eutrophication.