Ambient Monitoring System
Ambient Monitoring System (AMS)
The AMS consists of a network of stations established to provide site-specific, long-term water quality information on significant rivers, streams, and estuaries throughout the state. The program has been active for over forty years. Stations are visited at least quarterly for the collection of a variety of physical, chemical, and bacterial pathogen samples and measurements. Details of the program design and implementation can be found in the Quality Assurance Project Plan (QAPP) and SOP. General information on objectives, indicators measured, and data availability is provided below.
The AMS' primary objectives are:
- To monitor waterbodies of interest for determination of levels of chemical, physical, and bacterial pathogen indicators for comparison to a selection of the state's water quality standards.
- To identify locations where exceedances of water quality standards for physical and chemical indicators occur in more than 10% of samples/measurement (20% for coliforms).
- To identify long-term temporal or spatial patterns.
Data produced by the AMS are also used to support several DWR water quality management programs, including Basin Water Resources Plan development, biennial 305(b) and 303(d) reporting to EPA, TMDL development, and development of NPDES permit limits.
Currently there are 329 active AMS stations. Stations are located in all seventeen major river basins of the state, and in 95 of North Carolina's 100 counties.
The AMS focuses primarily on chemical, physical, and bacterial pathogen characteristics of the water column. The indicators are primarily selected from those chemicals that have current state water quality standards and can be cost-effectively analyzed. Additional indicators are also included that may not have specific associated standards but are useful for interpretation of other measurements. Others are, of themselves, useful for identifying long-term trends.
A basic core suite of indicators is measured at all stations. These include water temperature, specific conductance, pH, turbidity, total suspended residue, DO, fecal coliform, and weather conditions. Additional indicators may be included depending on site-specific concerns such as stream classification, discharge types, and historical or suspected issues. Examples of these site-specific indicators include salinity, Secchi depth, flow, nutrients (NH3, NO2+NO3, TKN, TP), fluoride, sulfate, total hardness, color, oil and grease, and chlorophyll a. Residue is sampled quarterly at all stations and total hardness is measured quarterly at all freshwater stations. All other indicators are sampled at least quarterly. A full sampling schedule is included in Appendix 3 of the QAPP.
Long term indicator sites
A portion of AMS stations have been identified as long term indicator sites due to their on-going collection of data dating back to before 1980. The data from these sites are evaluated on an annual basis to summarize regional trends across North Carolina for dissolved oxygen (DO), turbidity, and fecal coliform bacteria. The most recent summary can be found here.
Design and Implementation
All data collected as part of the AMS over the last 40+ years are readily available online from the U.S. EPA's STORET database. The warehouse currently contains over 5 million AMS results, and approximately 100,000 new records are added annually. AMS staff have developed a guidance document to assist new users with downloading data from STORET. A data explanations document is also available, which was originally developed to assist with interpreting data retrievals obtained directly from the AMS program, but it also provides general information on station codes and data caveats.
In addition to storing raw results in STORET, AMS data are summarized by basin and reported as part of the Water Sciences Section's Ambient Monitoring System Summary Reports and, previously, Basin Assessment Reports.
|Brian Pointer||Ambient Monitoring System Coordinator||919.743.8411