West Virginia
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West Virginia water profile

Nitrate in West Virginia community water systems

West Virginia's nitrate gathers where its karst is: the limestone eastern panhandle around Martinsburg and Charles Town, where groundwater has been documented moving at hundreds of feet per day. See where the pattern concentrates and what each reporting system measured in the three years from August 9, 2023 to August 9, 2026.

Browse all 414 West Virginia systems →

Search by the utility or system name shown on a water bill. Example: City of Martinsburg. Private wells are not in this inventory.

99%
of the state’s 417 active community water systems have a current result here
414
systems with a current nitrate result
1,550,431
people served by those reporting systems
2.7%
of reporting systems at or above 5 mg/L
How to read these numbers Each system is placed into a band by its most recent reported result within a rolling three-year window. The bands describe how strongly human activity, read from nitrate, has marked a water source; they are not a safety verdict. Figures describe system reporting, not nitrate measured at an individual tap.

How West Virginia's systems fall across the five bands

Most systems report below 3 mg/L

Natural background
0.00–0.99 mg/L as N
337 systems · 1,243,824 served
Human impact likely
1.00–2.99 mg/L as N
50 systems · 190,391 served
Human impact clear
3.00–4.99 mg/L as N
16 systems · 90,654 served
Health-study range
5.00–9.99 mg/L as N
11 systems · 25,562 served
Above the federal limit
10.00 mg/L and above
0 systems · 0 served

Each system appears in one band only, placed by its most recent reported result in the current three-year window. Counts sit beside people served so a small number of larger systems cannot hide behind a row of tiny ones. Of the 11 systems reporting 5 mg/L or more, 3 stayed at or above 5 across the whole three-year range; the other 8 reached it only on a high sample and otherwise ran lower.

Most recent reading Jun 2026; the typical system was last tested around Jan 2026. 227 systems sampled their own water; 187 systems carry a supplier’s result.

The named systems

Every reading here belongs to a utility with a name

Highest recent readings
SystemMost recent resultBandBased onPeople served
Wvaw - Walnut Grove Utilities7.04 mg/LMay 2026a high point — runs lowerHealth-study range58 samples7,250
Charles Town Utl-Cavaland Subdivision6.91 mg/LMay 2026a high point — runs lowerHealth-study range12 samples107
Mason Water Dept6.49 mg/LMay 2026Health-study range9 samples1,679
Mason Co Psd-Foglesong Dist6.49 mg/LMay 2026Health-study rangeinherited from supplier156
Mason Co Psd-Lakin Dist6.30 mg/LMay 2026Health-study range13 samples4,296
Potomac Farms Water Co6.10 mg/LAug 2024Health-study range4 samples65
Williamstown Water Dept5.91 mg/LJun 2026Health-study range12 samples3,469
Wvaw - Cave Quarter Utility5.57 mg/LJun 2026Health-study range12 samples126
Largest systems
SystemMost recent resultBandBased onPeople served
Wvawc-Kanawha Valley Dist0.19 mg/LApr 2026Natural background3 samples209,283
Wvawc - Huntington Dist0.53 mg/LOct 2025Natural background3 samples98,647
Morgantown Utility Board0.37 mg/LApr 2026Natural background3 samples64,644
Beckley Water Company0.23 mg/LJan 2026Natural background6 samples47,386
Berkeley County Pswd-Potomac River1.30 mg/LApr 2026Human impact likely4 samples34,786

Each result shows its date and what it rests on, so a lone sample is never taken for a settled measurement. A single high sample is not a complete account of what a household drinks.

Where higher nitrate concentrates

Higher results gather in the karst panhandle

Human impact is clear on drinking water served in seven of West Virginia’s 55 counties. Each is shaded by how many of its systems reported 3.00 mg/L as N or above. Shading counts systems, not severity — a county with many small utilities can outrank one holding a single larger system that reads higher. The table beside the map splits the two bands so that difference stays visible.

WV counties shaded by number of community water systems reporting nitrate at or above 3.00 mg/L as NCounties are shaded by how many community water systems reported nitrate at or above 3.00 mg/L as N in the three years from August 9, 2023 to August 9, 2026. The same counts appear in the table below this map.Wetzel County — 3 systems at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveWood County — 2 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveHancock County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveJefferson County — 2 systems at 3.00–4.99 mg/L as N; 4 systems at 5.00 mg/L as N or aboveBerkeley County — 4 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveJackson County — 1 system at 3.00–4.99 mg/L as N; 2 systems at 5.00 mg/L as N or aboveMason County — 3 systems at 3.00–4.99 mg/L as N; 3 systems at 5.00 mg/L as N or above
none1–23–56–1112–2526+Number of drinking water systems reporting ≥3.00 mg/L NO₃–N per county as of August 9, 2026

Jefferson leads this layer with 4 reporting systems, followed by Mason, Jackson, Berkeley. Higher results gather in the karst panhandle. Coverage note: the map places 99% of West Virginia’s reporting systems. All 3 of the rest buy their water and carry their supplier’s result, which was measured at the supplier’s source — shading their own county would put the reading in the wrong place. They are counted in the figures above.

Counties with the most systems at or above 3 mg/L as N
County3–4.99≥5Total ≥3
Jefferson246
Mason336
Berkeley415
Jackson123
Wetzel303

Counts use each system's most recent reported result in the current three-year window. A system appears in only one of the two bands. Coverage note: the map places 99% of West Virginia’s reporting systems. All 3 of the rest buy their water and carry their supplier’s result, which was measured at the supplier’s source — shading their own county would put the reading in the wrong place. They are counted in the figures above.

Find a specific West Virginia system

What the statewide pattern says

Fast limestone under farms and subdivisions

West Virginia's documented nitrate sits in the eastern panhandle karst — Great Valley limestone under orchards, poultry and Washington-commuter growth, studied by USGS since the 1960s.

The eastern panhandle is one of the longest-studied karst aquifers in the country. USGS sampling in Jefferson County found 14 percent of 192 wells at or above the 10 mg/L federal limit in 1981; a decade later the follow-up found 26 percent of wells and springs over the limit, with fecal bacteria at half the sites (Kozar, 2002 — USGS karst investigations synopsis). Dye tracing showed why: groundwater there moves 70 to 840 feet per day along bedding, so a sinkhole or septic field connects to a well in days.

The driving land uses are agriculture and growth together — orchards and poultry in the Great Valley, plus one of the fastest Washington-commuter build-outs in the state on individual wells and septic. Berkeley County's karst work found bacteria the bigger problem and nitrate patchier; Jefferson carries the nitrate signature (USGS SIR 2016-5048).

The Ohio River corridor counties — Mason, Jackson, Wood — form the map's second, thinner cluster on alluvial and fractured-rock ground. The published nitrate literature there is thin, so this page marks the readings without claiming a certified source. About 90 percent of West Virginia's rural population drinks groundwater (USGS Fact Sheet 48-95).

The supported source reading is agricultural and septic nitrogen on fast karst in the panhandle — not a certified source at any individual system (Nolan and Hitt, 2006).

The general science — how nitrate moves, why some ground is vulnerable, and why the legacy lingers — is laid out with its sources on Where nitrate comes from.

Questions this page answers

What the West Virginia pattern does—and does not—say

Where does nitrate concentrate in West Virginia community water systems?

Jefferson leads this layer with 4 reporting systems, followed by Mason, Jackson, Berkeley. Higher results gather in the karst panhandle.

How fast does contamination move in the West Virginia panhandle?

At karst speed. USGS dye tracing in Jefferson and Berkeley Counties measured groundwater moving 70 to 840 feet per day along bedding planes — orders of magnitude faster than ordinary aquifers. That is why the same studies found fecal bacteria at roughly half of sampled sites alongside the nitrate.

Has panhandle nitrate gotten better or worse?

Worse, in the studied record. Jefferson County went from 14 percent of wells at or above the federal limit in 1981 to 26 percent of wells and springs a decade later, as development added septic load to the agricultural base. Berkeley County's karst showed bacteria as the larger problem and nitrate patchier.

Does a high public-system result mean a nearby private well is high?

No. It is a local sentinel, not a well-specific result. It shows that nitrogen and a transport pathway have reached groundwater in the area; a certified-lab test is still the only way to know a specific private well.

Sources and provenance

What this page rests on

  1. NitrateSmart inventory: 414 West Virginia community water systems with a current nitrate result in the three years from August 9, 2023 to August 9, 2026. Figures count people served by reporting systems, not measured tap exposure.
  2. Nolan BT, Hitt KJ (2006). Vulnerability of Shallow Groundwater and Drinking-Water Wells to Nitrate in the United States. Environmental Science & Technology 40(24):7834–7840.
  3. Dubrovsky NM, and others (2010). Nutrients in the Nation's Streams and Groundwater, 1992–2004. USGS Circular 1350.
  4. Kozar MD (2002). Synopsis of karst investigations in Jefferson and Berkeley Counties, West Virginia. USGS WRI 02-4174 — 14% of Jefferson wells at/above MCL (1981), 26% of wells and springs (1991); dye-traced flow 70–840 ft/day.
  5. USGS (2016). Hydrogeologic terrains and surface-water-influenced groundwater supplies in West Virginia. Scientific Investigations Report 2016-5048 — the eastern panhandle karst study record from Bieber (1961) forward.
  6. USGS (1995). United States Geological Survey Programs in West Virginia. Fact Sheet 48-95 — ~90% of the rural population depends on groundwater; about a quarter of Jefferson County karst sites with excessive nitrate.