Lake Oswego Municipal Water
EPA ID: OR4100457 · 40,000 people served · 4 ZIP codes
ZipCheckup's reading of EPA SDWIS for Lake Oswego Municipal Water (OR4100457): 2 EPA violations in the last five years. While 2 violations did appear in Lake Oswego Municipal Water's five-year monitoring record, none remain unresolved - the utility has returned to full compliance and continues to serve approximately 40,000 residents under all current EPA drinking water standards.
Data: EPA SDWIS
Service Area Map
Coverage area for Lake Oswego Municipal Water Source: EPA SDWIS service area boundaries.
Service area boundary - Grade A
Service Area Demographics
The Lake Oswego Municipal Water serves a community with a median household income of $136,372 and an estimated 120,359 residents across its service area. Approximately 62% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
🌊 Where Does Your Water Come From?
Lake Oswego Municipal Water's water is drawn from rivers, lakes, or reservoirs. Surface water sources are more exposed to agricultural runoff, stormwater, and upstream discharges, but they typically receive more intensive treatment before reaching your tap.
Superfund Proximity Note: This service area ranks in the 70th percentile nationally for proximity to Superfund (NPL) sites.
Infrastructure Risk
Detected Contaminants
How Lake Oswego Municipal Water compares to EPA limits
What This Means For You
Surface Water Treatment Rule at 2 mg/L exceeds the EPA maximum of mg/L.
Comparable Water Systems
Similar-sized systems in Oregon
Estimated Remediation Costs
Average estimated costs across ZIP codes served by this system
Based on national averages for common remediation projects. Actual costs vary by property. Only issues flagged by EPA, FEMA, or state data for each ZIP code are included.
System Overview
Lake Oswego Municipal Water (EPA ID: OR4100457) is a community water system in Oregon that serves approximately 40,000 people from surface water sources.
This system provides water to 4 ZIP codes across 3 communities.
ZIP-Area Home Safety Context: A (96/100)
This is the average Home Safety Score for 2 of 4 service-area ZIP codes with all required score domains observed. It is not a grade for the water utility.
Model 4.0.0 uses SDWIS identity plus accepted ECHO SDWA lifecycle-based water compliance, the UCMR 5 PFAS MCL screen, EPA radon zone, and annual EPA AirData AQI across three equally weighted domains. Missing required evidence suppresses the score.
Violation History
Status breakdown for accepted records with record years 2021-2026: 2 resolved, 0 archived, 0 addressed, and 0 unaddressed. Under this source contract, current noncompliance is the sum of addressed and unaddressed records. Archived and resolved records are excluded from current noncompliance.
Recent Violations
| Date | Contaminant | Type | Status |
|---|---|---|---|
| July 1, 2025 | Surface Water Treatment Rule | Non-health-based | Resolved |
| July 1, 2024 | Surface Water Treatment Rule | Non-health-based | Resolved |
Contaminants Detected
The following contaminants have been flagged in EPA records for this water system:
| Contaminant | Category | Violations | Health-Based |
|---|---|---|---|
| Surface Water Treatment Rule | Treatment Failure | 2 | No |
Lead & Copper
EPA Lead and Copper Rule evidence attributed directly to this water system:
| Lead Level | Exceeds Action Level | Sample Date |
|---|---|---|
| 0 mg/L | No | N/A |
No copper action-level exceedance record appears for this PWSID in the accepted LCR snapshot. This does not establish a clean copper measurement.
Radon Risk in Service Area
Dominant radon zone for ZIP codes served by this system: Zone 3 (Low Risk)
Need help with your water quality?
Typical cost: Water test: typically $20–$50 (DIY kit) · Professional inspection: $150–$400
Find the Right Water FilterFree tip: Let cold water run for 2 minutes before drinking — this helps flush lead from your pipes.
ZIP Codes Served
Coverage: Service area ZIP codes sourced from EPA Community Water System Service Area Boundaries v3 (March 2026 release). These ZIPs reflect the actual deployment footprint recorded by OR or modeled from parcel and building-footprint data.
Data Sources
This report uses public data from the EPA Safe Drinking Water Information System (SDWIS). View the full compliance record for Lake Oswego Municipal Water (OR4100457) on EPA.gov.
Frequently Asked Questions
Is Lake Oswego Municipal Water water safe to drink?
The accepted 2026Q2 ECHO snapshot shows no current noncompliance for Lake Oswego Municipal Water; its 2 accepted 2021-2026 records are resolved or archived. Historical compliance status does not establish conditions at a specific tap.
How many people does Lake Oswego Municipal Water serve?
Lake Oswego Municipal Water serves approximately 40,000 people across 4 ZIP codes in Oregon.
Where does Lake Oswego Municipal Water get its water?
The primary water source is surface water.
Federal UCMR5 PFAS Monitoring: Tested Clean
This water system was tested under the federal EPA Unregulated Contaminant Monitoring Rule (UCMR5). No PFAS compounds were detected.
Current MCL reflects the lowest state-enforceable limit (NYS 10 ppt for PFOA/PFOS, effective August 2020). The federal final MCL of 4 ppt for PFOA/PFOS (EPA April 2024 rule) is not enforceable until April 2029. Detections above 4 ppt but below 10 ppt are below current MCL but above the future federal limit.
Source: U.S. EPA UCMR5 (Unregulated Contaminant Monitoring Rule, 5th cycle) — per-system federal sampling, 2023–2025. EPA UCMR5 monitoring program →
How Water Systems Appear in Rankings
Water systems are evaluated by violation history, contaminant detections, and service population. Larger systems with more service connections appear in more rankings.
- #41 / 50 Highest Exposure Burden (Oregon)
Frequently Asked Questions
How to cite this page
ZipCheckup. (n.d.). Lake Oswego Municipal Water (OR): 2 EPA Violations. https://zipcheckup.com/water-system/or4100457/
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What You Can Do
Test your water
Home test kits can detect lead, bacteria, and other contaminants at your tap. Find the right filter →
Check your specific ZIP code
Water quality can vary within a system. View nearest ZIP report →
Contact your utility
Lake Oswego Municipal Water (EPA ID: OR4100457) - request the latest Consumer Confidence Report or ask about specific contaminants.