Currituck Sound

Back Bay, Currituck Sound, NC

Background

There continues to be concern about water quality in and the biological health of Currituck Sound. As development in the Currituck Sound watershed continues at a rapid pace, management strategies are needed to protect and enhance the quality of this resource (U.S. Army Corps of Engineers, 2001). The necessary tools and data are not, however, available to conduct an assessment of the effects of possible management strategies on salinity and water quality of the Sound.

In 1980, Currituck Sound Task Committee (North Carolina Department of Natural Resources and Community Development, 1980) recommended that State agencies “request the U.S. Geological Survey to assist in an evaluation of the hydrology of the Sound.” The Corps of Engineers also recognizes the need for a hydrodynamic model of Currituck Sound to characterize inflows to and outflows from the Sound, as well as circulation within the Sound (U.S. Army Corps of Engineers, 2001). Such a model can be used to evaluate the effects of both existing and possibly future hydrologic modifications on circulation and salinity in the Sound.

Previously-measured high nutrient concentrations and chronic algal blooms resulted in failure of Currituck Sound to qualify for designation as Outstanding Resource Waters (North Carolina Division of Environmental Management, 1994). There is, however, no recent water chemistry information that can be used to evaluate the current health of the Sound, nor are tools available to predict the response of Currituck Sound to changes in water-quality loadings.

Map of Study Area, Currituck Sound, NC

Objectives

A team of scientists has been assembled to address Currituck Sound problems. The team includes scientists from the Corps of Engineers (COE), North Carolina Division of Water Resources (NC DWR), Elizabeth City State University (ECSU), North Carolina Estuarine Research Reserve (NCERR), U.S. Fish and Wildlife Service (FWS), and the USGS. The USGS will provide support to various aspects of the overall Currituck Sound effort. Objectives of USGS activities are as follows:

Data Collection Approach

A variety of data will be collected during the overall Currituck Sound study. In general, USGS will collect discharge and velocity data, and ECSU, FWS, and NCERR will collect continuous water-quality data and discrete water samples.

Streamflow data is collected by the USGS at 6 sites (5 discharge, 1 velocity). The discharge data-collection network is designed to provide information on all inflows/outflows to/from the sound. Because of tidal influences in the sound, velocity is collected using the acoustic velocity meters, and discharge is determined using the index-velocity approach. All data are quality-assured and stored in the USGS NWIS database.

Continuous water-quality monitors are deployed at 8 sites (5 by ECSU, 2 by NCERR, and 1 by FWS). The USGS provides training to ECSU, NCERR and FWS scientists on deployment, calibration, recovery, and data downloading for the monitors, and perform occasional field quality-assurance checks. The USGS also provide guidance on initial data-processing. The USGS perform the final data processing and quality checks, and store the data in the USGS data base.

Discrete water samples are collected periodically by ECSU (5 sites), NCERR (2 sites) and USGS (1 site). Water–quality samples are analyzed by the University of North Carolina at Chapel Hill Institute of Marine Science and are periodically provided to the USGS and are stored in the USGS database.