Nitrate In Drinking Water In Montana
What residents of Montana need to know about nitrate in drinking water — including how it enters water, which utilities have documented violations, and what steps to take.
Source: EPA SDWIS, Montana Department of Environmental Quality (MDEQ), CDC · Last reviewed: 2025-01-01
Quick Answer
Is nitrate in drinking water a real concern in Montana?
Moderate — Montana's dryland wheat farming and cattle ranching generate some nitrate loading, but at lower intensity than corn belt or southeastern poultry states. Private well users in agricultural valleys should still test.
Is this mostly a public-water issue, a private-well issue, or both?
Primarily private well users in irrigated agricultural valleys and dryland farming areas; Montana's lower agricultural intensity relative to Midwest states means nitrate risk is present but generally lower.
What is the main reason residents should care?
Eastern Montana's dryland wheat farming and cattle ranching, and irrigated agriculture in river valleys (Yellowstone, Milk, and Sun River areas), contribute agricultural nitrate. Private wells in these areas may show elevated levels, particularly near feedlots or heavily fertilized irrigated fields.
Key Facts
| EPA Nitrate MCL | 10 mg/L as N |
| Relative risk | Lower than Midwest corn belt states — dryland wheat and cattle have less fertilizer intensity |
| Agricultural sources | Eastern plains wheat farming; cattle feedlots; irrigated valley agriculture |
| Natural sources | Some Montana geology has naturally occurring nitrate-bearing formations |
| State oversight | Montana Department of Environmental Quality (MDEQ) |
Why This Matters in Montana
Montana's agricultural sector is dominated by dryland wheat farming on the eastern plains and cattle ranching statewide, with some irrigated agriculture in major river valleys. This pattern produces lower fertilizer application intensity than the corn belt, but agricultural wells in eastern Montana farming communities and river valley irrigation districts can show elevated nitrate. Feedlot operations near small communities are a local concern. Montana also has natural nitrate from nitrate-bearing rock formations in some areas. MDEQ monitors public water systems for nitrate compliance and provides private well testing guidance. Private well testing is the owner's responsibility.
Critical — Infants Under 6 Months
Do not use tap water that exceeds 10 mg/L nitrate-nitrogen to prepare infant formula or feed infants under six months. Boiling will concentrate nitrate — do not boil. Use bottled water or a certified reverse osmosis system (NSF/ANSI 58) until the issue is resolved.
Montana Utilities With Nitrate Violation Records
The utilities listed below have at least one nitrate violation on record in EPA's SDWIS database. Violations may be open or resolved — see individual utility pages for current status and risk level.
How Nitrate Gets Into Drinking Water
Agricultural fertilizer and manure runoff
Nitrogen-based fertilizers and animal waste applied to Montana cropland can leach into groundwater or run off into surface water supplies. This is the dominant nitrate pathway in most agricultural regions.
Septic system effluent
Failing or poorly sited septic systems release nitrogen-rich wastewater near drinking water wells. Rural areas with high well density and aging septic infrastructure face elevated risk.
Concentrated animal feeding operations (CAFOs)
Large livestock facilities generate significant waste. Lagoon leaks and overapplication of manure to nearby fields can create localized nitrate hotspots in groundwater.
Natural geological deposits
In some regions, naturally occurring nitrogen compounds in soil and bedrock contribute background nitrate levels to groundwater independent of agricultural activity.
Who Should Pay Closest Attention
Private well users in eastern Montana dryland farming communities and irrigated valley areas should test for nitrate, particularly if located near feedlots or heavily fertilized fields. Annual testing is recommended for all agricultural-area wells.
Households with infants under six months
Pregnant residents
Private well owners in agricultural areas
Households near livestock operations or CAFOs
Rural residents on shallow groundwater wells
Households with older or failing septic systems nearby
How to Check Your Situation in Montana
- 1
Identify your water utility. Use the ZIP lookup below or browse the Montana utility directory on this site.
- 2
Read your utility's page on this site to see its current risk level and any open nitrate violations.
- 3
Review your utility's most recent Consumer Confidence Report (CCR) — mailed annually or available on the utility's website. It must disclose any MCL exceedances.
- 4
If you are on a private well, arrange testing at a Montana Department of Environmental Quality (MDEQ)-certified lab. Your state health department maintains a list of certified labs. Annual testing is recommended in agricultural areas.
- 5
If you have an infant under six months, use bottled water or a certified RO system (NSF/ANSI 58) immediately as a precautionary measure — do not wait for test results if you are in a high-risk area.
- 6
If your utility issues a nitrate exceedance notice, follow their guidance and do not use tap water for infants until the issue is resolved.
Treatment Options
Carbon filters and boiling do not remove nitrate. Only the options below are effective.
NSF/ANSI Standard 58 — Reverse Osmosis
RO systems certified to NSF/ANSI 58 reduce nitrate by 85–95% at the point of use. Under-sink installation required. The most practical residential option for nitrate concerns.
Distillation
Distillation units effectively remove nitrate along with most other dissolved contaminants. Suitable for drinking and cooking water — not whole-house use.
Anion Exchange
Ion exchange systems designed for nitrate removal exchange nitrate ions for chloride on a resin bed. Effective as a point-of-entry system; requires periodic regeneration and monitoring.
Carbon filters do NOT remove nitrate
Standard pitcher filters, faucet filters, and under-sink carbon units — including those certified NSF/ANSI 42 or 53 — do not remove nitrate. Do not use these for nitrate reduction.
Frequently Asked Questions
Related Pages
Nitrate — National Overview
All U.S. utilities with nitrate records
Montana State Overview
All utilities and water quality data
Lead in Drinking Water
A separate but common concern
Reverse Osmosis Guide
Removes 85–95% of nitrate
Well Water Guide
Private well testing and safety
All Contaminants
Complete reference library
Data Sources & Provenance
All data on this page is sourced from official U.S. government or public datasets.
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Montana Department of Environmental Quality (MDEQ) ↗