Nash County at 122.5× the Federal Limit: What the Refreshed UCMR 5 Data Tells Us

Introduction

This morning I refreshed the PFAS dataset behind our dashboard against the latest EPA UCMR 5 occurrence data and USGS Water Quality Portal records. The headline numbers for North Carolina are worth sitting with: 290 public water systems with usable results, 119 sites exceeding federal Maximum Contaminant Levels, and 47 counties with at least one system above the limit. The single worst reading in the state — a system in Nash County at 122.5 times the federal MCL — is the kind of number that should end any debate about whether PFAS is a localized problem in this state. It is not. It is a statewide infrastructure problem wearing a chemistry costume.

What the numbers actually say

UCMR 5 (the Fifth Unregulated Contaminant Monitoring Rule) is the most comprehensive PFAS sampling campaign ever run on American drinking water, covering 29 PFAS compounds across thousands of public water systems. For North Carolina, the refreshed cut shows detections at 176 public water supply sites spanning 70 counties. Detections are not violations — many are trace-level hits below health thresholds — but the 119 sites that exceed the EPA's 2024 drinking water standards are.

A few patterns stand out in the data:

1. Geography follows industry and hydrology. The heaviest exceedances cluster in the Cape Fear basin (legacy Chemours/Fayetteville Works influence), the Research Triangle's growth corridor, and several Piedmont counties with textile and manufacturing histories. This is consistent with what fate-and-transport science predicts: PFAS follows industrial discharge points downstream and accumulates in alluvial aquifers.
2. Small systems are disproportionately exposed. A large municipal utility can amortize a $5–10 million GAC or ion-exchange installation across hundreds of thousands of ratepayers. A system serving 4,000 people cannot. The per-household cost math for small-system compliance is the sleeper crisis inside these numbers.
3. The worst sites are not where most people look. Nash County is not the county most North Carolinians associate with PFAS — the Cape Fear gets the headlines. That is precisely why statewide occurrence data matters more than anecdote-driven monitoring.

Why 122.5× deserves scrutiny, not panic

A 122.5× exceedance sounds catastrophic, and it is serious — but context matters. UCMR 5 reports maximum observed concentrations, and PFAS occurrence can vary with season, pumping rates, and well rotation. What a number like this tells a scientist is: there is a strong, nearby source, and the plume is not attenuating. The correct response is source investigation and exposure reduction, in that order — not alarm, and not complacency either.

For residents in affected areas, the practical questions are concrete: Is my water system notifying me? (It is required to, under the 2024 rule's public notification provisions.) What treatment is planned, and on what timeline? Is bottled or filtered water warranted in the interim? These are questions utilities should be answering proactively, in plain language, before residents have to ask.

The compliance clock is the real story

Here is what converts these numbers from interesting to urgent: EPA's 2024 drinking water regulation requires public water systems to complete initial monitoring by 2027 and comply with the MCLs by 2029. We are now inside that window. Every system on our dashboard showing an exceedance is a system with a capital project to plan, fund, and build — on a timeline that is shorter than it looks once you account for design, permitting, and procurement.

For the 47 North Carolina counties with exceedances, the next 18 months are the decision window. Systems that start treatability studies and funding applications now (through the Bipartisan Infrastructure Law's PFAS-dedicated funding and the state revolving funds) will meet 2029. Systems that wait for the monitoring deadline will not.

What I am watching next

Three things: (1) whether North Carolina's EMC finalizes permanent state groundwater standards, which would extend this pressure from drinking water systems to industrial dischargers and remediation sites; (2) how small-system funding actually flows — the dollars exist, but the application burden falls hardest on the utilities least equipped to carry it; and (3) the next UCMR 5 data release, which will fill in systems still completing their sampling. I will keep this dashboard current as each release lands. The data is the easy part. The decisions it forces are the hard part.