Much of North Carolina’s Triangle — Raleigh, Durham, Chapel Hill and the towns around them — draws its drinking water from rivers and reservoirs. A fast-growing population has transformed the landscape: urban and suburban growth adds new sources of nutrients and contaminants and raises demand for water, while climate change and regional water use affect how much is available.
The Triangle Area Water Supply Monitoring Project (TAWSMP), a partnership between the U.S. Geological Survey and local governments, keeps watch over those supplies.
A partnership since 1988
The project began in 1988, after B. Everett Jordan Lake (in the Cape Fear Basin) and Falls Lake (in the Neuse Basin) were completed. Its local partners include the Towns of Apex, Cary, Hillsborough and Morrisville, the City of Durham, Chatham and Orange Counties, the Orange Water and Sewer Authority and the Central Pines Regional Council.
The project's nine phases since 1988, each with its focus, and the years of its major and minor reports. Graphic: U.S. Geological Survey.
Its goal is to find out whether nutrients or emerging contaminants are affecting Triangle water supplies, where they come from, and whether things are getting worse over time. Each phase runs approximately 3–5 years, with a focus set by the partners’ changing needs, and USGS publishes reports on the results.
Phase IX: emerging contaminants
The current phase runs from 2022 to 2027 and samples every monitoring site for:
- 1,4-dioxane
- bromide
- PFAS (per- and polyfluoroalkyl substances)
A synthesis report is planned near the end of the phase. Routine monitoring continues alongside:
- sampling six times a year at nine reservoir locations and four streams and rivers that feed them
- sampling stormwater runoff at selected tributaries, adding to state-led efforts
- running 10 streamgages that report streamflow in real time
Eric von Amsberg collecting a water-quality sample on the Haw River below B. Everett Jordan Dam, near Moncure. Photo: Ryan Rasmussen, U.S. Geological Survey.
Deanna Hardesty taking water-quality measurements at the University Lake intake near Chapel Hill. Photo: Ryan Rasmussen, U.S. Geological Survey.
Ryan Rasmussen retrieving samples from an automated sampler during a flood on Northeast Creek near Genlee. Photo: Stephen Harden, U.S. Geological Survey.
Why measure the flow?
Streamgages show how much water flows into and out of the reservoirs over time. That helps to:
- trace where nutrients and contaminants come from, how they travel and how much each stream contributes
- understand the effects of reservoir operations and plan long-term water management
- track how management practices and climate change affect water availability
Why measure water quality?
Nutrients from wastewater treatment plants, urban runoff and farms wash into streams and reservoirs. Too much feeds algae, especially in warm weather, and some algae make water taste or smell bad or produce cyanotoxins harmful to people and animals. The project’s data feed models — used by USGS, researchers and the North Carolina Department of Environmental Quality — that measure nutrient and sediment loads and test whether efforts to reduce them are working.
Contaminants can enter from factories, runoff and wastewater plants. Water suppliers already test treated drinking water as state and federal rules require, including for the rotating list of emerging contaminants in the EPA’s Unregulated Contaminant Monitoring Rule, reviewed every 5 years. The project complements that testing by monitoring the source water itself, for longer and more flexibly — together giving a fuller picture of the risks to the Triangle’s water.
Sources
Based on "Triangle Area Water Supply Monitoring Project, North Carolina," U.S. Geological Survey Fact Sheet 2024–3032, prepared in cooperation with Triangle-area local governments; a work of the United States government in the public domain. The photographs and timeline are reproduced from the fact sheet.
Licence: CC0 1.0 (public domain) · Adapted from pubs.usgs.gov
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