Public water system · CO0130100
ActiveMountain Wsd
At a glance
Mountain Wsd (PWSID CO0130100) is an active community water system in Jefferson County, Colorado. It reports serving 1,941 people through 399 service connections. Its primary water source is groundwater under influence of surface water, and EPA lists it as owned by a local government. Of the 12 most recent violations in EPA's records, 6 are health-based, and the most recent began in April 2026.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
1,941
Service connections
399
Primary source
GU
Groundwater under influence of surface water
System type
CWS
Community water system
System record
How does Mountain Wsd compare with other water systems in Jefferson County?
By EPA's size categories, Mountain Wsd is a small system (501 to 3,300 people). Jefferson County has 112 active public water systems. Its population served is about 62% below the county average of 5,159 people per system, and accounts for 0.3% of the 577,783 people reported by systems filed under the county. Across Colorado, the 2,207 active systems average 3,400 people each. Nationally, the average active community water system reports serving 6,703 people, so Mountain Wsd is well below that figure.
What does “community water system” mean?
A community water system serves at least 15 connections used by year-round residents, or regularly serves at least 25 year-round residents. Homes, apartments and mobile-home parks are served by these. Colorado has 1,068 active community water systems, 48% of the state's 2,207 active systems. Groundwater under the influence of surface water is well or spring water that the regulator has found to be affected by nearby surface water, so it is regulated under the surface-water treatment rules. 166 Colorado systems (7.5%) list groundwater under influence of surface water as their primary source.
Who owns and regulates Mountain Wsd?
EPA lists Mountain Wsd as owned by a local government. The CO state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 39 of the 112 active systems in Jefferson County (35%) are also owned by a local government.
Does Mountain Wsd have drinking water violations?
Of the 12 most recent violations in EPA's records, 6 are health-based, and the most recent began in April 2026. The violations listed here began between January 2010 and April 2026. By type: 5 contaminant level above the legal limit, 5 monitoring and reporting, 1 public notice, recordkeeping or other and 1 required treatment not met. The contaminant or rule involved most often is Combined Uranium (3 of them). EPA lists 10 as resolved, 1 as unaddressed and 1 as archived. Resolved means at least one resolving action is on record: the system returned to compliance, the rule no longer applies, or no further action was needed. Unaddressed means the violation is not resolved or archived and is not yet covered by formal enforcement. Archived means the violation was not marked resolved but is more than five years past the end of the noncompliance period, so it no longer counts toward current compliance status.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2026-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Gross alpha (excluding radon and uranium)code 4000 | Yes | Unaddressed |
| 2026-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Gross alpha (excluding radon and uranium)code 4000 | Yes | Archived |
| 2025-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2024-10-01 | Monitoring and reportingMonitoring, Turbidity (Enhanced SWTR) · code 38 | Interim Enhanced Surface Water Treatment Rulecode 0300 | No | Resolved |
| 2024-10-01 | Monitoring and reportingMonitoring of Treatment (SWTR-Filter) · code 36 | Surface Water Treatment Rulecode 0200 | No | Resolved |
| 2024-05-01 | Required treatment not metMonthly Turbidity Exceed (Enhanced SWTR) · code 44 | Interim Enhanced Surface Water Treatment Rulecode 0300 | Yes | Resolved |
| 2020-12-01 | Monitoring and reportingMonitoring of Treatment (SWTR-Filter) · code 36 | Surface Water Treatment Rulecode 0200 | No | Resolved |
| 2013-05-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 2013-04-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Chlorinecode 0999 | No | Resolved |
| 2011-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Combined Uraniumcode 4006 | Yes | Resolved |
| 2010-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Combined Uraniumcode 4006 | Yes | Resolved |
| 2010-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Combined Uraniumcode 4006 | Yes | Resolved |
The 12 most recent violations in EPA's records, newest first.Labels and codes come from EPA's SDWIS reference tables. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found. "Health-based" marks violations of a legal limit or required treatment.
Mountain Wsd: frequently asked questions
Who runs Mountain Wsd?
Mountain Wsd (PWSID CO0130100) is a community water system owned by a local government. It is regulated by the CO state drinking water program.
How many people does Mountain Wsd serve?
Mountain Wsd reports serving 1,941 people through 399 service connections in Jefferson County, Colorado.
Where does Mountain Wsd get its water?
EPA SDWIS lists this system's primary water source as groundwater under influence of surface water. Groundwater under the influence of surface water is well or spring water that the regulator has found to be affected by nearby surface water, so it is regulated under the surface-water treatment rules.
Does Mountain Wsd have any drinking water violations?
Of the 12 most recent violations in EPA's records, 6 are health-based, and the most recent began in April 2026. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found.
Is Mountain Wsd's water safe to drink?
AquaCensus shows EPA compliance records, not current water test results, so it cannot say whether the water is safe at a given moment. Of the 12 most recent violations in EPA's records, 6 are health-based, and the most recent began in April 2026. For current results, consult the system's annual water quality report, EPA ECHO, or the CO state drinking water program.
Where can I find Mountain Wsd's water quality report?
As a community water system, Mountain Wsd must deliver an annual water quality report, called a Consumer Confidence Report, to its customers by July 1 each year, covering the previous calendar year. The system can provide a copy on request.
Other water systems in Jefferson County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Arvada City of | Jefferson | 171,610 | Community | Surface water |
| Consolidated Mutual Maple Grove | Jefferson | 81,400 | Community | Surface water |
| Green Mountain Wsd | Jefferson | 49,400 | Community | Purchased surface water |
| Bancroft Clover Wsd | Jefferson | 44,000 | Community | Purchased surface water |
| Golden City of | Jefferson | 38,288 | Community | Surface water |
| Bear Creek Wsd | Jefferson | 30,000 | Community | Purchased surface water |
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About this data
Source: U.S. EPA Safe Drinking Water Information System (SDWIS) and SDWA violation records, via EPA ECHO, as published October 1, 2026 — AquaCensus refreshes it quarterly. See the methodology for how records are matched, cleaned and scored.
Cite as: AquaCensus, “Mountain Wsd, PWSID CO0130100, Colorado”, https://aquacensus.com/water-systems/colorado/mountain-wsd-co0130100 (data as of October 1, 2026).