This report constitutes the first phase to document the water quality benefits of a stream restoration in the coastal plain of North Carolina. This phase establishes the pre-restoration state of the water quality and hydrochemical signature of ‘the canal’ at the Claridge nursery in Goldsboro, NC, for comparison purposes with the during and after restoration phases. Because classical indicators of water quality (i.e., concentrations and loads) are calculated from infrequent samples (e.g., often monthly), these indicators are stained with large uncertainties (20%-50% or even higher). Classical monitoring methods are thus ill suited to detect and quantify water quality benefits of stream restoration, expected to be at or less than 20%. To have a chance to capture water quality benefits of a stream restoration, we have proposed to use state of the art monitoring equipment able to measure flow and concentrations at a high resolution in time, hoping to reduce uncertainties enough to detect and quantify stream restoration effects.
We have used UV-Vis spectrophotometers as index data source and created Water Quality Rating Curves to obtain concentration data on a high frequency basis to calculate robust N, P, C, and material fluxes. In articular, we have shown that in the ‘Claridge Canal’ agricultural stream of the coastal plain of North Carolina, it was possible to construct robust Water Quality Rating Curves to measure nitrate, TDN, TKN, DOC, and TP, using the absorbance data as index data and Partial Least Square Regression (PLSR) as a rating method. We have also shown that this method did not work well for NH4-N and PO4-P. We show that the uncertainty on annual cumulative loads was within 3% for most parameters. This gives a chance to capture restoration effects that would be at least twice this value.
