City of Mountlake Terrace
EPA ID: WA5357250 · 26,402 people served · 2 ZIP codes
ZipCheckup's reading of EPA records for City of Mountlake Terrace (WA5357250): 1 violation on record since 2021. City of Mountlake Terrace's EPA record lists 1 historical violation, and none is listed as open in that record; the utility supplies water to 26,402 residents.
Data: EPA SDWIS
Service Area Map
Coverage area for City of Mountlake Terrace Source: EPA SDWIS service area boundaries.
Service area boundary - average Home Safety grade of mapped ZIPs: A
Demographics of ZIP Codes Served
The ZIP codes associated with City of Mountlake Terrace have a median household income of $95,487 and about 63,433 residents live in those ZIP codes (Census; not the number of people this system supplies). Approximately 66% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
🌊 Where Does Your Water Come From?
City of Mountlake Terrace'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.
Infrastructure Risk
Comparable Water Systems
Similar-sized systems in Washington
System Overview
City of Mountlake Terrace (EPA ID: WA5357250) is a community water system in Washington that serves approximately 26,402 people from surface water sources.
This system provides water to 2 ZIP codes across 2 communities.
ZIP-Area Home Safety Context: A (100/100)
This is the average Home Safety Score for 1 of 2 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: 1 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, 2024 | Consumer Confidence 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 |
|---|---|---|---|
| Consumer Confidence Rule | Other (notice or report rule) | 1 | No |
Lead & Copper
No reported lead measurement appears for this PWSID in the accepted LCR snapshot. Absence of a reported measurement is not a measured zero.
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
2 of 2 ZIP records with known zones are in EPA Radon Zone 3.
The EPA recommends testing all homes regardless of radon zone. County radon zones cannot replace an in-home radon test.
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 WA 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 available EPA compliance records for City of Mountlake Terrace (WA5357250) on EPA.gov.
Frequently Asked Questions
Is City of Mountlake Terrace water safe to drink?
The accepted 2026Q2 ECHO snapshot shows no current noncompliance for City of Mountlake Terrace; its 1 accepted 2021-2026 record are resolved or archived. Historical compliance status does not establish conditions at a specific tap.
How many people does City of Mountlake Terrace serve?
City of Mountlake Terrace serves approximately 26,402 people across 2 ZIP codes in Washington.
Where does City of Mountlake Terrace get its water?
The primary water source is surface water.
Federal UCMR5 PFAS Monitoring: No PFAS Reported Above Reporting Levels
This water system was tested under the federal EPA Unregulated Contaminant Monitoring Rule (UCMR5). No PFAS compounds were reported above UCMR5 minimum reporting levels.
EPA's April 2024 PFAS rule sets MCLs of 4 ppt for PFOA and PFOS and 10 ppt for PFHxS, PFNA and HFPO-DA (GenX); water systems must comply from 2029. Other PFAS compounds have no individual federal MCL. A state standard is shown only where this system's state has its own enforceable PFAS limit. Detection results are EPA UCMR5 samples, not a measurement at your tap.
Source: U.S. EPA UCMR5 (Unregulated Contaminant Monitoring Rule, 5th cycle) — per-system federal sampling, 2023–2025. EPA UCMR5 monitoring program →
Frequently Asked Questions
How to cite this page
ZipCheckup. (n.d.). City of Mountlake Terrace (WA): 1 EPA Violation. https://zipcheckup.com/water-system/wa5357250/
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title = {{City of Mountlake Terrace (WA): 1 EPA Violation}},
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url = {https://zipcheckup.com/water-system/wa5357250/}
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What You Can Do
Test your water
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Check your specific ZIP code
Water quality can vary within a system. View nearest ZIP report →
Contact your utility
City of Mountlake Terrace (EPA ID: WA5357250) - request the latest Consumer Confidence Report or ask about specific contaminants.