Public water system · ID4010247
ActiveArrowrock Ranch
At a glance
Arrowrock Ranch (PWSID ID4010247) is an active community water system in Ada County, Idaho. It reports serving 250 people through 100 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 December 2013.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
250
Service connections
100
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Arrowrock Ranch compare with other water systems in Ada County?
By EPA's size categories, Arrowrock Ranch is a very small system (500 people or fewer). Ada County has 87 active public water systems. Its population served is well below the county average of 5,880 people per system, and accounts for less than 0.1% of the 511,514 people reported by systems filed under the county. Across Idaho, the 1,961 active systems average 899 people each. Nationally, the average active community water system reports serving 6,703 people, so Arrowrock Ranch 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. Idaho has 765 active community water systems, 39% of the state's 1,961 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 1,861 Idaho systems (95%) list groundwater as their primary source.
Who owns and regulates Arrowrock Ranch?
EPA lists Arrowrock Ranch as privately owned. The ID state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 71 of the 87 active systems in Ada County (82%) are also privately owned.
Does Arrowrock 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 December 2013. The violations listed here began between April 2007 and December 2013. By type: 11 monitoring and reporting and 1 contaminant level above the legal limit. The contaminant or rule involved most often is Radium-226 (2 of them). EPA lists 11 as archived and 1 as resolved. 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. 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.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2013-12-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
| 2008-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Radium-226code 4020 | No | Archived |
| 2008-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Radium-226code 4020 | No | Archived |
| 2007-07-01 | Monitoring and reportingInitial Tap Sampling for Pb and Cu · code 51 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2007-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Toxaphenecode 2020 | No | Archived |
| 2007-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Xylenes, Totalcode 2955 | No | Archived |
| 2007-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Benzenecode 2990 | No | Archived |
| 2007-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Vinyl chloridecode 2976 | No | Archived |
| 2007-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | 1,1,1-Trichloroethanecode 2981 | No | Archived |
| 2007-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Trichloroethylenecode 2984 | No | Archived |
| 2007-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | trans-1,2-Dichloroethylenecode 2979 | No | Archived |
| 2007-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Alachlor (Lasso)code 2051 | No | Archived |
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.
Arrowrock Ranch: frequently asked questions
Who runs Arrowrock Ranch?
Arrowrock Ranch (PWSID ID4010247) is a community water system privately owned. It is regulated by the ID state drinking water program.
How many people does Arrowrock Ranch serve?
Arrowrock Ranch reports serving 250 people through 100 service connections in Ada County, Idaho.
Where does Arrowrock 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 Arrowrock 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 December 2013. 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 Arrowrock 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 December 2013. For current results, consult the system's annual water quality report, EPA ECHO, or the ID state drinking water program.
Where can I find Arrowrock Ranch's water quality report?
As a community water system, Arrowrock Ranch 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 Ada County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Veolia Water Idaho | Ada | 264,978 | Community | Surface water |
| Meridian Water Dept | Ada | 147,340 | Community | Groundwater |
| Kuna City of | Ada | 32,038 | Community | Groundwater |
| Star Sewer and Water Dist Water System | Ada | 14,000 | Community | Groundwater |
| Garden City Water and Sewer System | Ada | 12,500 | Community | Groundwater |
| Capitol Water Corp | Ada | 9,000 | Community | Groundwater |
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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, “Arrowrock Ranch, PWSID ID4010247, Idaho”, https://aquacensus.com/water-systems/idaho/arrowrock-ranch-id4010247 (data as of October 1, 2026).