Water Quality in Yellowstone National Park, WY: 1 Violation — Grade C
Grade C · Score 66/100 · 1 water system · Updated 2026-05-03
Yellowstone National Park's water has moderate compliance issues. Residents in affected areas should consider filtration.
Data: EPA Safe Drinking Water Information System (SDWIS) Last verified: 2026-05-03
Tracked under the EPA Safe Drinking Water program, Yellowstone National Park, WY shows 1 water violation on file — findings that span multiple violation categories and are detailed system by system in the data grid further down the page.
Water Quality by ZIP Code in Yellowstone National Park
Water quality varies across Yellowstone National Park's 1 ZIP codes. Check your specific ZIP for detailed contaminant data.
| ZIP Code | Grade | Score | Violations | Health | |
|---|---|---|---|---|---|
| 82190 | C | 66 | 1 | 0 | View report → |
Water Quality Overview
Yellowstone National Park, Wyoming receives a water quality grade of C with an overall score of 66 out of 100, based on EPA compliance data from the Safe Drinking Water Information System (SDWIS).
The 1 water system serving Yellowstone National Park have accumulated 1 EPA violations (all monitoring/reporting type). These violations are tracked across 1 ZIP codes serving approximately 2,600 people.
What Grade C Means
A grade of C indicates moderate compliance issues. Yellowstone National Park's water systems have some violations that warrant attention. While the water may still be safe for most people, residents in affected ZIP codes should consider additional testing or filtration.
Lead Levels
The average 90th percentile lead level across Yellowstone National Park water systems is 0.0040 mg/L — within EPA limits. No ZIP codes exceed the EPA lead action level.
With 56% of homes built before 1986, Yellowstone National Park has a higher-than-average risk of lead from older plumbing. Lead solder was banned in 1986, and homes built before this date may have lead in pipes, solder joints, or fixtures.
Radon Risk
Yellowstone National Park is in EPA Radon Zone 1 (High risk). The EPA recommends all homes in Zone 1 areas be tested for radon. Radon is the second leading cause of lung cancer after smoking.
Water Systems Serving Yellowstone National Park
Yellowstone National Park is served by 1 community water system regulated under the Safe Drinking Water Act. These systems collectively serve approximately 2,600 people across 1 ZIP codes.
Each water system is identified by a Public Water System ID (PWSID) and is required to:
- Test for over 90 regulated contaminants on a regular schedule
- Report results to the EPA and state regulators
- Issue an annual Consumer Confidence Report (CCR) to all customers
- Take corrective action when violations occur
The EPA has taken 2 enforcement actions against water systems serving Yellowstone National Park. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in Yellowstone National Park
Enter your ZIP code on ZipCheckup to see your specific water system data, including contaminant levels, violation history, and safety scores
Request your CCR — your water utility must provide an annual Consumer Confidence Report with detailed test results for all monitored contaminants
Get a home test — certified kits cost $20–$50 and test for lead, bacteria, and common contaminants. Professional lab tests ($150–$400) cover a broader panel
Consider filtration — NSF-certified filters can remove specific contaminants. Reverse osmosis removes the broadest range; activated carbon is effective for chlorine and many organics
Check for advisories — monitor your local utility website and local news for boil water advisories or system alerts
Contaminants Detected in Yellowstone National Park Water Systems
The following contaminants have been detected or caused violations across Yellowstone National Park's water systems:
| Contaminant | Category | MCL | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|---|
| E. coli | Microbiological | N/A | 1 | 1 | No |
MCL = Maximum Contaminant Level (EPA enforceable standard). Health-based violations indicate levels that may pose direct health risks.
EPA Enforcement History
The EPA and state regulators have taken 2 enforcement actions against water systems serving Yellowstone National Park. Recent actions:
| Date | Action Type |
|---|---|
| 2023-11-08 | State Order Extension |
| 2023-10-05 | State Informal Action |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2023-11-08.
Yellowstone National Park vs. Nearby Wyoming Cities
How Yellowstone National Park's water quality compares to similar cities in Wyoming:
| City | Grade | Violations | Systems | Population |
|---|---|---|---|---|
| Yellowstone National Park | C | 1 | 1 | 2,600 |
| Afton | C | 4 | 5 | 2,647 |
| Lovell | C | 6 | 2 | 2,510 |
| Wright | B | 1 | 1 | 2,500 |
Common Questions About Yellowstone National Park Water
These are the most common questions residents search for about water quality in Yellowstone National Park, Wyoming:
Is Yellowstone National Park water hard or soft? Water hardness varies by source. Yellowstone National Park's 1 water system uses a single source. Check your ZIP code report for specific hardness data.
Can I drink Yellowstone National Park tap water? Yellowstone National Park's water receives a grade of C (66/100). No health-based violations have been recorded, but home testing is always recommended.
What is the best water filter for Yellowstone National Park? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.
Yellowstone National Park vs. Wyoming Average
Understanding how Yellowstone National Park compares to the broader Wyoming average helps contextualize your local water quality. Factors like water source, treatment methods, and infrastructure age all contribute to differences between cities in the same state.
To see how individual neighborhoods compare, check the ZIP code reports below — water quality can vary significantly even within Yellowstone National Park.
ZIP Codes in Yellowstone National Park
Yellowstone National Park spans 1 ZIP code. The ZIP with the lowest water quality score is 82190. Each ZIP code has its own water quality profile based on the specific water system serving that area. Check each ZIP code for detailed contaminant data, violation history, and system information.
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Lead/copper: EPA Lead and Copper Rule sampling data
- Radon: EPA Map of Radon Zones
- Enforcement: EPA ECHO database
- Filter recommendations: NSF/ANSI certified products
Updated daily.