Nitrate In Drinking Water In Oregon
What residents of Oregon 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, Oregon Health Authority — Drinking Water Services (OHA DWS), CDC · Last reviewed: 2025-01-01
Quick Answer
Is nitrate in drinking water a real concern in Oregon?
Yes — the Willamette Valley and eastern Oregon have documented agricultural nitrate concerns in groundwater. Southern Willamette Valley groundwater has been studied for elevated nitrate from grass seed and vegetable farming.
Is this mostly a public-water issue, a private-well issue, or both?
Primarily private well users in the Willamette Valley and eastern Oregon agricultural areas; some small public systems in agricultural zones also monitor elevated nitrate.
What is the main reason residents should care?
The Willamette Valley's intensive grass seed, vegetable, and orchard farming generates nitrate loading. Eastern Oregon's irrigated farming and cattle ranching contribute agricultural nitrate in some groundwater areas. OHA has documented nitrate in some portions of Willamette Valley groundwater.
Key Facts
| EPA Nitrate MCL | 10 mg/L as N |
| Willamette Valley | Intensive grass seed and vegetable farming — documented elevated nitrate in southern WV groundwater |
| Eastern Oregon | Cattle ranching and irrigated farming contribute agricultural nitrate in some areas |
| Private well risk | Southern Willamette Valley and eastern OR agricultural county well users — annual testing |
| State oversight | Oregon Health Authority — Drinking Water Services (OHA DWS) |
Why This Matters in Oregon
Oregon's Willamette Valley — stretching from Eugene to Portland — is one of the most productive agricultural areas in the Pacific Northwest, with intensive grass seed production, hazelnuts, wine grapes, vegetables, and other crops. The southern Willamette Valley (Lane and Benton Counties) has documented elevated nitrate in groundwater from agricultural activity. Eastern Oregon supports cattle ranching, irrigated potato and grain farming, and dairy operations that contribute nitrate loading. OHA's Drinking Water Services monitors public water systems for nitrate compliance and provides private well testing guidance. The Oregon Health Authority has documented nitrate in some portions of agricultural-area groundwater.
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.
Oregon 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.
Salem Public Works
Oregon · 199,820 served
Medford Water Commission
Oregon · 106,068 served
City of Hillsboro
Oregon · 92,632 served
Klamath Falls Water Dept
Oregon · 40,475 served
Lake Oswego Municipal Water
Oregon · 40,000 served
City of Keizer
Oregon · 38,585 served
Redmond Water Department
Oregon · 37,566 served
City of Grants Pass
Oregon · 37,138 served
Clackamas River Water
Oregon · 29,918 served
City of Woodburn
Oregon · 29,455 served
How Nitrate Gets Into Drinking Water
Agricultural fertilizer and manure runoff
Nitrogen-based fertilizers and animal waste applied to Oregon 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 the southern Willamette Valley (Lane, Benton, Linn Counties) and eastern Oregon agricultural communities should test for nitrate annually. Households with infants relying on private well water should test before formula preparation.
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 Oregon
- 1
Identify your water utility. Use the ZIP lookup below or browse the Oregon 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 Oregon Health Authority — Drinking Water Services (OHA DWS)-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
Oregon 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.