USGS North Carolina WSC - Projects - Currituck Sound

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.

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:

Element 1 (Data Collection): Collect discharge data at key locations, train ECSU, NCERR, and FWS scientists in the collection of continuous water-quality data and discrete water samples, provide quality assurance for all project data collection, and process and store data in the USGS database. Click here for agency assignments.

Element 2 (Compilation of Existing Data): Compile relevant historical data on Currituck Sound water-quality conditions, assemble data in a database, and provide some preliminary data analysis.

Element 3 (Water-Quality Modeling Support): Provide quality assurance for the water-quality model being developed by the COE, provide advice to the NC DWR on model performance, and participate in model testing and application.

Element 4 (Data report preparation): Several agencies have contributed funds and effort to conduct a fairly comprehensive data-collection program in Currituck Sound. Data collection by the USGS began in December 2005, and other groups began data collection in 2006. A complete set of hydrologic and water-quality data will be available for the period July 1, 2006 – July 31, 2007. A report will document the data collect efforts of the study.

Element 5 (Watershed model development and application): The USDA model SWAT (Soil & Water Assessment Tool, http://www.brc.tamus.edu/swat/) will be used to simulate flow and concentrations of sediment, phosphorus, and nitrogen to Currituck Sound. SWAT has a GIS interface that allows spatial data to be fairly easily imported to the model.

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.

Project Overview

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Currituck Sound

Project Summary