Effectiveness of the Neuse River Nutrient Management Strategy: A Case Study on the Influence of Land Use

Abstract

Due to its vital role in contributing to the ecosystem of the APES and as a recreational and water supply watershed, the quality of water running through the Neuse River is very important to the state of North Carolina. However, the Neuse River Basin has been plagued by poor water quality primarily caused by an influx of nutrients attributed to anthropogenic sources such as agricultural and stormwater runoff. Over saturation of nitrogen and phosphorus within the basin led to eutrophic conditions, ultimately causing algal blooms, increased turbidity, low dissolved oxygen, and fish mortality. Consequently, the Neuse River was first identified as an impaired water body per Section 303(d) of the Clean Water Act in 1988. Management efforts have been in place since 1988. However, decades later the goals of the Neuse Management Strategy have not been met, and the Neuse River remains classified as nutrient sensitive waters with impaired status. This study aimed to evaluate potential sources of nutrient-enriched runoff within the basin by using Geographical Information Systems (GIS) to identify areas of developed and agricultural land with the highest potential for runoff within two representative counties, Lenoir and Wake. Results indicated that agricultural cultivated cropland was thelargest land use category in the Neuse River basin, accounting for 838,686 acres or 21% of the entire basin. Within Lenoir County there were 8,394 acres of agricultural land with a high potential for agricultural runoff, 79,066 acres with moderate potential, and 15,245 acres with low potential. In comparison, Wake County had 785 acres of agricultural lands with high potential for runoff, 18,778 acres with moderate potential, and 4,676 acres with low potential for agricultural runoff. Agriculture-based Lenoir County contained 2,128 acres of land with high potential for stormwater runoff, 21,704 acres with moderate potential, and 4,723 acres with low potential. The more developed Wake County had 28,119 acres with high potential for stormwater runoff. This was followed by an additional 147,132 acres with moderate potential, and 59,537 acres with low potential for stormwater runoff. This study suggests that significant nonpoint sources of nutrient-polluted runoff still remain within the Neuse River Basin. Although a Nutrient Management Strategy exists for the Neuse River, it may not be adequately protective against nutrient inputs from nonpoint sources. If the current rules are not eliciting the desired water quality outcomes it is unlikely that the water quality will improve or even hold steady as the population, and corresponding urban development and agricultural operations, continues to grow . Regulatory authorities should consider additional management approaches, especially for nonpoint nutrient sources.