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Wyoming water profile

Nitrate in Wyoming community water systems

Wyoming's nitrate signal is small but sharply placed: it sits in the irrigated North Platte valley of Goshen and Platte counties, where sugar beets and corn grow on some of the fastest-draining soils in the state. 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 319 Wyoming systems →

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

99%
of the state’s 323 active community water systems have a current result here
319
systems with a current nitrate result
535,379
people served by those reporting systems
2.8%
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 Wyoming's systems fall across the five bands

Most systems report below 3 mg/L

Natural background
0.00–0.99 mg/L as N
266 systems · 447,230 served
Human impact likely
1.00–2.99 mg/L as N
30 systems · 67,891 served
Human impact clear
3.00–4.99 mg/L as N
14 systems · 7,533 served
Health-study range
5.00–9.99 mg/L as N
8 systems · 12,630 served
Above the federal limit
10.00 mg/L and above
1 system · 95 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 9 systems reporting 5 mg/L or more, 4 stayed at or above 5 across the whole three-year range; the other 5 reached it only on a high sample and otherwise ran lower.

Most recent reading Jul 2026; the typical system was last tested around Sep 2025. 233 systems sampled their own water; 86 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
Cottonwood Acres14.30 mg/LJun 2026a high point — runs lowerAbove the federal limit38 samples95
Stone Creek Hoa9.60 mg/LJun 2026a high point — runs lowerHealth-study range12 samples100
Torrington Municipal Water Dept, City Of8.60 mg/La high point — runs lowerHealth-study rangeCCR summary, unverified6,847
South Torrington Water District8.60 mg/La high point — runs lowerHealth-study rangeinherited from supplier450
Albin, Town Of7.80 mg/LJun 2026a high point — runs lowerHealth-study range26 samples181
Valley View Mutual Water Company7.30 mg/LJun 2026Health-study range12 samples100
Pine Bluffs, Town Of7.00 mg/LMar 2024Health-study range*1 sample1,186
Hide-A-Way Mobile Village5.80 mg/LApr 2026Health-study range12 samples107
Largest systems
SystemMost recent resultBandBased onPeople served
Cheyenne Board Of Public Utilities0.49 mg/LSep 2025Natural background6 samples64,165
Casper, City Of0.36 mg/LNatural backgroundCCR summary, unverified59,000
Laramie, City Of1.94 mg/LNov 2025Human impact likely12 samples32,395
Gillette, City Of0.30 mg/LNatural backgroundCCR summary, unverified32,222
Jackson, Town Of1.05 mg/LHuman impact likelyCCR summary, unverified24,760

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 sit in the North Platte valley

Human impact is clear on drinking water served in six of Wyoming’s 23 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.

WY 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.Lincoln County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or abovePlatte County — 2 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveGoshen County — 4 systems at 3.00–4.99 mg/L as N; 4 systems at 5.00 mg/L as N or aboveTeton County — 3 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveFremont County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveLaramie 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

Goshen leads this layer with 4 reporting systems, followed by Laramie, Platte, Teton. Higher results sit in the North Platte valley. Coverage note: the map places 97% of Wyoming’s reporting systems. Of the rest, 6 carry a supplier’s result measured elsewhere and belong off this map; 2 sampled their own water and are missing a county in the records, so the map reads as a floor by at least that much.

Counties with the most systems at or above 3 mg/L as N
County3–4.99≥5Total ≥3
Goshen448
Laramie336
Teton314
Platte213
Fremont101

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 97% of Wyoming’s reporting systems. Of the rest, 6 carry a supplier’s result measured elsewhere and belong off this map; 2 sampled their own water and are missing a county in the records, so the map reads as a floor by at least that much.

Find a specific Wyoming system

What the statewide pattern says

Sugar-beet irrigation on fast soils

Wyoming's higher nitrate is a North Platte valley story: decades of irrigated farming on highly permeable soils above a shallow alluvial aquifer that also supplies the valley towns.

Goshen County is Wyoming's most concentrated farming ground, and its nitrate problem is documented in unusual detail. The valley towns — Torrington, Lingle, Fort Laramie — draw drinking water from the North Platte alluvial aquifer, the same shallow aquifer that sits under the irrigated fields. USDA analyses rate the valley's predominant soils as high-leaching (permeability above 6 inches per hour), and University of Wyoming work has tracked nitrate in the aquifer for decades (University of Wyoming Water Resources Center).

The mechanism is partly geological bad luck. A University of Wyoming wellhead study for Torrington found that Brule Formation bedrock outcrops act as underground dams: nitrate from intensively farmed terrace land stagnates behind them, then spills through breaches straight into the floodplain aquifer that feeds the municipal wellfield. A citizen-monitoring network across the county measured nitrate up to 53.6 mg/L — more than five times the federal limit — in wells just outside the river floodplain, with concentrations peaking during the growing season (Reddy and Goertler, 1998).

The rest of the state runs low: Wyoming's map is one farm valley plus a thin scatter, including Teton County, where the signal is growth and septic on alluvial ground rather than row crops. About three-quarters of Wyoming's population drinks groundwater, so the valley's alluvial setting matters beyond the towns (Wyoming Water Resources Center).

The supported source reading is irrigated row-crop nitrogen — corn and sugar beets — on high-leaching soils over the alluvial aquifer — not a certified source at any individual system. The valley fits the national pattern of nitrate risk where heavy nitrogen input meets fast infiltration (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 Wyoming pattern does—and does not—say

Where does nitrate concentrate in Wyoming community water systems?

Goshen leads this layer with 4 reporting systems, followed by Laramie, Platte, Teton. Higher results sit in the North Platte valley.

Why is Wyoming's nitrate problem so localized?

Because the state has exactly one intensive irrigation district on highly permeable soils over a shallow drinking-water aquifer: the North Platte valley in Goshen and Platte counties. USDA rates those soils high-leaching, and University of Wyoming studies have measured nitrate above the federal limit there for decades. Most of the rest of the state is rangeland on slower ground.

What is the bedrock-dam effect under Torrington?

University of Wyoming modelers found that Brule Formation bedrock outcrops block groundwater flow, so nitrate-charged water from farmed terraces pools behind them and then funnels through gaps directly into the floodplain aquifer that supplies the Torrington municipal wellfield — geology concentrating what farming supplies.

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: 319 Wyoming 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. University of Wyoming Water Resources Center (1993). Torrington Area Wellhead Groundwater Problem Identification — Brule bedrock dams stagnate and funnel agricultural nitrate into the municipal wellfield aquifer.
  5. Reddy KJ, Goertler CM (1998). Citizen’s Network for Monitoring Groundwater Quality in Goshen County, Wyoming. Wyoming Water Resources Center — nitrate to 53.6 mg/L outside the floodplain, ~5× the MCL during the growing season.
  6. USDA Natural Resources Conservation Service. A tiered approach to nitrogen management — Goshen County case: high-leaching Dunday/Dwyer/Haverson soils; Lingle, Fort Laramie and Torrington wells testing above the MCL; WWRC vulnerability study rated the alluvium highly vulnerable.