What Weekly River Testing Tells Us About Water Safety in WNC

Every week during the warmer months, crews collect water samples from rivers and creeks across Western North Carolina. The goal is simple: help the public understand when local waterways may carry higher health risks during swimming, tubing, or kayaking. 

The monitoring is run by the North Carolina Department of Environmental Quality (North Carolina Department of Environmental Quality) through its Division of Water Resources (North Carolina Division of Water Resources), with lab work completed in Asheville.

At the center of the testing is a familiar name: E. coli.

A warning signal in the water

E. coli is a bacteria commonly found in the environment and in the intestines of people and animals. It is not always harmful, but higher levels can signal that other germs linked to illness may also be present.

That’s why state health officials, including the North Carolina Department of Health and Human Services (North Carolina Department of Health and Human Services), use it as an early warning tool for recreational water safety.

How the process works

From May through September, testing sites are sampled once a week. The water is taken to a lab in Asheville and analyzed using a standard method. Results are usually available the next day.

But officials caution that these results are only a snapshot. River conditions can change quickly, especially after rain.

What the numbers mean

Results are measured in bacteria levels per 100 milliliters of water. Health guidance uses two key benchmarks:

126 or less — lower risk for swimming and direct contact

Above 126 — increased risk for illness during swimming

Above 886 — higher risk even for tubing or kayaking

These levels are based on federal water quality guidance used by state health officials.

Why conditions may change quickly

Mountain rivers are constantly moving. After heavy rain, runoff can carry bacteria into the water or stir up what is already present.

Because of that, a river that looks clear can still have elevated bacteria levels—and conditions can change from one day to the next, scientists say.

What the program is meant to do

State officials say the goal is not to label rivers as simply “safe” or “unsafe,” but to give the public real-time information during peak recreation season.

The data helps swimmers, paddlers, and families make informed decisions before heading into the water.

In fast-changing mountain waterways, that snapshot can make a difference.

The public map is available on the NCDEQ dashboard. Historical data is available for download dating back to 2025