THE HISTORICAL INFLUENCE OF PAPER MILL DISCHARGE ON THE SURFACE WATER QUALITY AND STREAM ECOLOGY OF THE PIGEON RIVER, NORTH CAROLINA

The Blue Ridge Paper Products Mill was a corrugated paper mill located in Canton, North Carolina that operated from 1908 until May 2023. For the better part of seven decades, the mill discharged waste into the Pigeon River with few repercussions. However, significant legal challenges and national coverage of its pollution resulted in the US EPA issuing a strict discharge permit in 1990. We analyzed constituent concentration data and benthic macroinvertebrates spanning a 40-year period from the Pigeon River to determine i) if, and to what degree the mill influenced the constituents; ii) the distance downstream it took for the river to return to conditions similar to those upstream of the mill; and iii) if, and to what degree the 1990 discharge permit influenced the quality of the river downstream of the mill.

The data analyzed originated from four sites on the Pigeon River at differing lengths above (-X Km = control) and below (+ X, X, and X km = impact) the mill’s discharge. These data were analyzed using analysis of covariance (ANCOVA) which were interpreted using pair-wise post-hoc tests via the emmeans tool in R. Trends amongst different sites were determined using analysis of variance (ANOVA) and the non-parametric Kruskal-Wallis test. Results indicate that the mill negatively influenced turbidity, true color, dissolved oxygen, phosphate-phosphorus as P, inorganic nitrogen as N, and benthic macroinvertebrates downstream of its discharge. Many of the analyzed constituents trended back towards conditions similar to those upstream of the mill after the 1990’s; however, the length of time and distance it took varied by site and metric. Additionally, certain metrics saw a sharp decrease in the early 1990’s when the discharge permit formally came into effect, indicating the overall effectiveness and success of the permit. While much improved, the river is still in a state of recovery. This is especially true for sites closest to the mill, as concentrations of true color, dissolved oxygen and benthic macroinvertebrates have yet to recover to conditions similar to those upstream of the mill. We encourage entities to continue monitoring constituents after the closing of the mill to document their trajectories.