Water Resources Research Act Program

Principal Investigators: Curtis Richardson, Mark River

Abstract: Over 500,000 residents of the NC Triangle region rely on surface water reservoirs in the 770 square mile Falls Lake Watershed (FLW) for their drinking water, which is protected at the Federal level (Safe Drinking Water Act), State level (Watershed Protection Act), and local level (Falls Lake Critical Area). Falls Lake itself is currently listed as an impaired waterbody on the Federal 303d list for total suspended solids (TSS). In the Triangle region and many watersheds, the vast majority of annual nitrogen (N) and phosphorus (P) loading occurs during storms, with much of this delivery consisting of nutrients attached to particulates (Cosser 1989, Richardson et al. 2011, Duan et al. 2012, Janke et al. 2014), yet no method has been developed to-date to easily quantify particulate nutrient loadings. Our newly developed particle/nutrient sizing approach in both urban and rural streams along with flow data from the USGS, suggests that integrated sediment-nutrient predictions are key to improving water quality in the NC Piedmont. Moreover our preliminary data suggest a new innovative way to easily predict N and P inputs into downstream water bodies. In highly-weathered landscapes such as the Piedmont, much of these particulate nutrients are sorbed to iron oxide coatings on clay particles, and therefore are transported along with the sediment. Thus, size of particles really matters as it directly relates to the movement and storage of particulate nutrients.