USGS - science for a changing world

South Atlantic Water Science Center

Map of North Carolina highlighting the project study area

Project Overview

Full Title
Rating Unsaturated Zone and Watershed Characteristics of Public Water Supplies - 2009 Updates


Cooperating Agencies
Public Water Supply Section
Source Water Assessment and Protection Program

Project Chief
Silvia Terziotti

Period of Project
1/2009 - 6/2009

Team Members
Kirsten Tighe
Ramona Traynor

Rating Unsaturated Zone and Watershed Characteristics of Public Water Supplies - 2009 Updates

This project was completed in 2009. These pages are for historical purposes only.


Cary Water Tower, North Carolina

Cary Water Tower, North Carolina. Photo by Roger Ehrlich.

The 1996 Amendments to the Safe Drinking Water Act require that each state prepare a source-water assessment for all public water supplies. States are required to (1) delineate source areas supplying wells and surface-water intakes, (2) inventory potential contaminant sources within the delineated source areas, and (3) determine the susceptibility of wells or intakes to the inventoried potential contaminant sources. North Carolina's Source Water Assessment Program (SWAP) provides assessments of each public drinking water intake in North Carolina. These assessments provide a relative susceptibility rating calculated using state-wide data.

In 1999, the U.S. Geological Survey (USGS) cooperated with the Public Water Supply Section (PWSS) of the Division of Environmental Health, Department of Environment and Natural Resources (DENR) to provide components of the inherent vulnerability rating that were used with the contaminant rating to determine the overall susceptibility rating of source water supplies.

In 2009, the USGS cooperated with the PWSS to update key layers of the unsaturated zone and watershed characteristic rating using the methodology developed for the 1999 project work. The methods are available in the publication Methods of rating unsaturated zone and watershed characteristics of public water supplies in North Carolina (Eimers, 2000), available online at href="">