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About the Data

What is the System Wide Monitoring Program?

Monitoring is collecting and analyzing data to observe and follow the condition of the estuaries. Over time, the data could show changing conditions in an estuary and can give clues to the causes of such changes.

The System-wide Monitoring Program (SWMP; pronounced “swamp” and established in 1995) is the monitoring program of the National Estuarine Research Reserve System. SWMP tracks short-term variability and long-term changes in estuarine waters to understand how human activities and natural events can change ecosystems. It provides valuable long-term data on water quality and weather at frequent time intervals.

There are several common factors, or parameters, that reserve scientists measure, or monitor, in estuaries. These parameters can be divided into two categories: abiotic and biotic. Abiotic factors are the non-living components of an ecosystem. Biotic factors are the living components of an ecosystem. The NERRS currently measures physical and chemical water quality indicators, nutrients and the impacts of weather on estuaries. Expanded biological monitoring and tracking of changes in land use is now beginning at many of the reserves.

Where does the data come from?

To understand changes in estuaries, each reserve uses automated data loggers (automated instruments used to record water quality information) and weather stations.

Data loggers, also called data sondes, consist of a long casing tube packed with sensitive probes collecting water quality and biological data. Data loggers are placed in estuarine waters at monitoring stations with other monitoring equipment.

Weather stations are sensors that are placed high in the air in an estuary to collect atmospheric data at monitoring stations with other monitoring equipment.

What types of data are collected?

Water quality, weather, biological and nutrient data are currently collected via SMWP. Specifically, the following data are collected:

  • Water quality parameters measured include water temperature, water depth, salinity, pH, dissolved oxygen and turbidity (cloudiness or clarity).
  • Nutrient parameters measured include ammonium, nitrate, nitrite and ortho-phosphate.
  • The biological parameter measured includes chlorophyll a.
  • Weather parameters measured include temperature, wind speed and direction, relative humidity, barometric pressure, rainfall and photosynthetically active radiation (PAR). Collection of this data began in July 2001

View an animated interpretation of the NERRS System-Wide Monitoring Program. These series of animations and visualizations will make it fun and easier for you to understand why scientist monitor estuaries and what parameters they use to measure water quality and weather patterns in an estuary. (Requires Flash Player)

How often are the data collected?

At all NERR sites:

  • Water quality data is collected at four water quality stations (located within or adjacent to the Reserve) at 15-minute intervals.
  • Weather data is collected at least in one location within or adjacent to the Reserve every 5 seconds, averaged every 15 min.
  • Biological monitoring data (specifically chlorophyll a) is collected at four water quality stations (within or adjacent to the Reserve) on a monthly basis over a 24-hour period
  • Nutrient data is collected at four water quality stations (within or adjacent to the Reserve) on a monthly basis, and over a full tidal cycle (or 24-hour, whichever is greater) at one of the stations.

How are the data quality assured and controlled?

For a monitoring program to be valued, the data collected must be accurate, representative and of sufficient duration. Accuracy requires a dataset to have been examined for wrong or missing data.

Quality assurance (QA), quality control (QC) and standard operating procedures (SOP) are separate components of a monitoring program that work together to provide data of known quality. Together they minimize and quantify the error that is introduced in sampling and allow the tracking of errors that might occur. QA/QC includes planning, assessment, reporting and making necessary changes to the water monitoring program to ensure quality data.

The NERRS Centralized Data Management Office (CDMO) provides QA/QC for the reserve system. CDMO is also responsible for maintaining and updating the NERRS standard operating procedures so that all SWMP data are collected in the same way across the nation.

Why is there a straight long line in the graph I generated?

The graph generated is missing data ranges. Unfortunately because of the software we are using to generate the graph, we cannot cut or hide the line.

Where are the data housed and how can I access them?

All SWMP data is housed and served through the NERRS Centralized Data Management Office (CDMO). To access the data visit:

From the CDMO website, archived - and now near-real time - water quality and weather data may be accessed. Also, NERRS boundary maps and station locations may be downloaded as either GIS shape files or Google Earth compatible files.

What is the policy for data citations?

National Oceanic and Atmospheric Administration, Office of Ocean and Coastal Resource Management, National Estuarine Research Reserve System-wide Monitoring Program. 2004. Centralized Data Management Office, Baruch Marine Field Lab, University of South Carolina


The dataset enclosed within this package/transmission are only as good as the quality assurance and quality control procedures outlined by the enclosed metadata reporting statement. The user bears all responsibility for its subsequent use/misuse in any further analyses or comparisons. The Federal Government does not assume liability to the Recipient or third persons, nor will the Federal Government indemnify the Recipient for its liability due to any losses resulting in any way from the use of this dataset.

For more information: Please visit the Centralized Data Management Office website. If you wish to receive notifications of system status and updates, please enter your information here


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