Public water system · WY5600631
ActiveMills Spring Ranch
At a glance
Mills Spring Ranch (PWSID WY5600631) is an active transient non-community water system in Natrona County, Wyoming. It reports serving 200 people through 8 service connections. Its primary water source is groundwater, and EPA lists it as privately owned. Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in January 2018.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
200
Service connections
8
Primary source
GW
Groundwater
System type
TNCWS
Transient non-community water system
System record
How does Mills Spring Ranch compare with other water systems in Natrona County?
By EPA's size categories, Mills Spring Ranch is a very small system (500 people or fewer). Natrona County has 48 active public water systems. Its population served is well below the county average of 1,680 people per system, and accounts for 0.2% of the 80,646 people reported by systems filed under the county. Across Wyoming, the 775 active systems average 838 people each. Nationally, the average active transient non-community water system reports serving 144 people, so Mills Spring Ranch is about 39% above that figure.
What does “transient non-community water system” mean?
A transient non-community water system serves places where people do not stay long, such as gas stations and campgrounds, and regularly serves at least 25 people a day for at least 60 days a year. Wyoming has 352 active transient non-community water systems, 45% of the state's 775 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 585 Wyoming systems (75%) list groundwater as their primary source.
Who owns and regulates Mills Spring Ranch?
EPA lists Mills Spring Ranch as privately owned. The WY state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 25 of the 48 active systems in Natrona County (52%) are also privately owned.
Does Mills Spring Ranch have drinking water violations?
Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in January 2018. The violations listed here began between April 2016 and January 2018. By type: 6 monitoring, 5 monitoring and reporting and 1 required treatment not met. The contaminant or rule involved most often is Revised Total Coliform Rule (7 of them). EPA lists 10 as resolved and 2 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. 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 |
|---|---|---|---|---|
| 2018-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitrate-Nitritecode 1038 | No | Resolved |
| 2017-08-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Archived |
| 2017-07-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Archived |
| 2017-01-01 | Required treatment not metTreatment Technique Startup Procedures (RTCR) · code 2D | Revised Total Coliform Rulecode 8000 | Yes | Resolved |
| 2016-09-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2016-08-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2016-07-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitritecode 1041 | No | Resolved |
| 2016-07-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2016-07-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitritecode 1041 | No | Resolved |
| 2016-06-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2016-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitritecode 1041 | No | Resolved |
| 2016-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitritecode 1041 | No | 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.
Mills Spring Ranch: frequently asked questions
Who runs Mills Spring Ranch?
Mills Spring Ranch (PWSID WY5600631) is a transient non-community water system privately owned. It is regulated by the WY state drinking water program.
How many people does Mills Spring Ranch serve?
Mills Spring Ranch reports serving 200 people through 8 service connections in Natrona County, Wyoming.
Where does Mills Spring Ranch get its water?
EPA SDWIS lists this system's primary water source as groundwater. Groundwater means the system draws its water from wells or springs fed by underground aquifers.
Does Mills Spring Ranch have any drinking water violations?
Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in January 2018. 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 Mills Spring Ranch'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, one is health-based, and the most recent began in January 2018. For current results, consult EPA ECHO, or the WY state drinking water program.
Where can I find Mills Spring Ranch's water quality report?
The annual Consumer Confidence Report requirement applies to community water systems. Mills Spring Ranch is a transient non-community water system, so it is not required to publish one; like every public water system, it must notify the people it serves about violations under EPA's public notification rules.
Other water systems in Natrona County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Casper, City of | Natrona | 59,000 | Community | Purchased surface water |
| Mills, City of | Natrona | 4,050 | Community | Groundwater under influence of surface water |
| Bar Nunn, Town of | Natrona | 4,000 | Community | Purchased surface water |
| Evansville, Town of | Natrona | 2,873 | Community | Surface water |
| Vista West Water Company | Natrona | 1,600 | Community | Purchased surface water |
| Pioneer Water & Sewer District | Natrona | 1,500 | 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, “Mills Spring Ranch, PWSID WY5600631, Wyoming”, https://aquacensus.com/water-systems/wyoming/mills-spring-ranch-wy5600631 (data as of October 1, 2026).