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Water-quality trends of the Albermarle-Pamlico estuary system—A progress report

North Carolina Department of Natural Resources and Community Development, Project abstracts for the period 1987-89
By Douglas A. Harned

Abstract

The objectives of this study are to identify, compile and analyze existing hydrologic and water quality data of the Albermarle-Pamlico estuary system (APES) in order to identify long-term temporal and spatial trends. Existing information on river and estuary water quality, agricultural land use and fertilizer use, and precipitation quality is being complied in a Statistical Analysis System (SAS) dataset. Additional data on land use, drainage density, and point sources will be complied as it becomes available.

The upstream boundary of the study area is defined by the watershed boundaries of the basins of the National Stream Quality Accounting Network (NASQAN) of the U.S. Geological Survey (USGS). Analysis of dissolved solids data from NASQAN stations on the Neuse River, Tar River, and Contentnea Creek shows a statistically significant increase of 1.5 mg/L per year over the last 20 years. Discharge data from these NASQAN stations is the best available long-term flow data for the APES system. A special effort will be made to relate the upstream water quality as monitored at the NASQAN stations to water quality in the estuary system. As part of this effort, monitors have been installed at the Neuse River at Kinston and Tar River at Tarboro NASQAN stations to continuously monitor specific conductance. The conductance data collected at these stations will allow comparison to data currently being collected at the USGS stations downstream in the estuaries.

Three principal sources of data supply water quality information for the APES area. A number of individual investigators have collected data for the system, the U.S. Environmental Protection Agency (EPA) database system STORET contains much of the N.C. Department of Natural Resources (NRCD) data, and the USGS database system WATSTORE contains NASQAN and atmospheric precipitation data of the National Atmospheric Deposition Program (NADP) network. A bibliography has been complied of reports by individual investigators for the APES area. Data from 25 of these reports has been entered into SAS data sets. Data has also been retrieved from WATSTORE for the seven NASQAN stations and is being obtained from STORET for most of the 450 stations listed in that database, including the NRCD Ambient Monitoring System. Maps of locations of the water-quality stations for the individual investigators and STORET data have allowed the identification of areas of missing data, and have helped break the region up into segments to ease water-quality comparisons. An examination of NADP data from the Lewiston and Clinton precipitation stations indicates that although pH of precipitation is low (around 4.5) there is no statistically significant trend over the last 10 years. However, water-quality variation in the rainfall may help to explain some of the water-quality variation observed in the estuary system.

Once the data set has been constructed, the data will then be analyzed to determine spatial variation and temporal trends. Relationships between estuary water quality and agricultural land use, fertilizer use, precipitation quality, and other hydrologic characteristics will be examined. Both parametric and non-parametric statistical techniques will be employed to determine trends and to identify correlations.

Harned, D.A., 1988, Water-quality trends of the Albemarle-Pamlico estuary system-A progress report [abs.], in North Carolina Department of Natural Resources and Community Development, Project abstracts for the period 1987-89: Raleigh, N.C., North Carolina Department of Natural Resources and Community Development, Albemarle-Pamlico Estuarine Study.