Ambient Monitoring System (AMS)

The Ambient Monitoring System (AMS) is a network of stations located throughout the state to provide site specific, long-term water quality information on North Carolina’s rivers, streams and estuaries.

Program Overview

Since the 1960s, the Ambient Monitoring System has collected water quality data in North Carolina’s 2.2 million acres of estuarine waters and ~38,000 miles of freshwater creeks, streams and rivers. The AMS consists of a relatively static network of more than 300 stations located in all 17 major river basins. These stations provide site specific, long-term water quality information on significant rivers, streams and estuaries. Stations are visited at least quarterly year-round for collection of chemical, physical and bacterial pathogen characteristics of the water column. AMS data are used to monitor and ensure compliance with the Clean Water Act and are publicly accessible through the Water Quality Portal. These data also support several Division of Water Resources’ water quality management programs including Basin Water Resources Plan development, biennial 305(b) and 303(d) reporting to the Environmental Protection Agency, Total Maximum Daily Load (TMDL) amounts, and development of NPDES permit limits. Details of the program design and implementation can be found in the Quality Assurance Project Plan and Standard Operating Procedures (SOPs).

Program Objectives

• Monitor water quality in waterbodies for comparison to NC water quality standards
• Identify locations where exceedances of NC water quality standards exist
• Determine long-term temporal and spatial trends

Monitoring Stations

Most AMS stations are monitored on a monthly basis. A core suite of indicators is measured at all stations. These include water temperature, specific conductance, pH, turbidity, total suspended residue (TSS), dissolved oxygen (DO), and fecal coliform. Additional indicators may be included depending on site-specific concerns such as stream classification, discharge types, and historical or suspected issues. Examples of site-specific indicators, which are monitored monthly or quarterly, include salinity, Secchi depth, flow, nutrients (NH3, NO2+NO3, TKN, TP), fluoride, sulfate, total hardness, color, oil and grease, and chlorophyll a.

Related Links

North Carolina Surface Water Quality Standards

Quality Assurance Project Plan

Physical/Chemical Monitoring SOP

Data Qualifier Codes and Analytical PQLs

Staff Contact