Public water system · IL0990800
ActiveOttawa
At a glance
Ottawa (PWSID IL0990800) is an active community water system in LaSalle County, Illinois. It reports serving 18,097 people through 8,049 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in October 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
18,097
Service connections
8,049
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Ottawa compare with other water systems in LaSalle County?
By EPA's size categories, Ottawa is a large system (10,001 to 100,000 people). LaSalle County has 129 active public water systems, and Ottawa is the 2nd-largest of them by population served. Its population served is about 22 times the county average of 816 people per system, and accounts for 17% of the 105,319 people reported by systems filed under the county. Across Illinois, the 3,872 active systems average 3,204 people each. Nationally, the average active community water system reports serving 6,703 people, so Ottawa is about 170% above 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. Illinois has 1,773 active community water systems, 46% of the state's 3,872 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 2,808 Illinois systems (73%) list groundwater as their primary source.
Who owns and regulates Ottawa?
EPA lists Ottawa as owned by a local government. The IL state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 20 of the 129 active systems in LaSalle County (16%) are also owned by a local government.
Does Ottawa have drinking water violations?
Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in October 2025. The violations listed here began between January 2020 and October 2025. By type: 10 monitoring and reporting, 1 reporting and 1 contaminant level above the legal limit. The contaminant or rule involved most often is Total trihalomethanes (TTHM) (3 of them). EPA lists 11 as resolved and 1 as unaddressed. 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.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2025-10-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Total trihalomethanes (TTHM)code 2950 | No | Resolved |
| 2025-10-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Haloacetic acids (HAA5)code 2456 | No | Resolved |
| 2025-07-02 | ReportingNotification, Known or Potential LSL · code 4H | Lead and Copper Rule Revisionscode 5200 | No | Unaddressed |
| 2023-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Combined Radium (-226 and -228)code 4010 | Yes | Resolved |
| 2023-01-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Haloacetic acids (HAA5)code 2456 | No | Resolved |
| 2023-01-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Total trihalomethanes (TTHM)code 2950 | No | Resolved |
| 2022-10-01 | Monitoring and reportingMonitoring, Regular · code 03 | Combined Radium (-226 and -228)code 4010 | No | Resolved |
| 2022-07-01 | Monitoring and reportingMonitoring, Regular · code 03 | Combined Radium (-226 and -228)code 4010 | No | Resolved |
| 2022-01-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Total trihalomethanes (TTHM)code 2950 | No | Resolved |
| 2022-01-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Haloacetic acids (HAA5)code 2456 | No | Resolved |
| 2020-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Styrenecode 2996 | No | Resolved |
| 2020-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Styrenecode 2996 | 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.
Ottawa: frequently asked questions
Who runs Ottawa?
Ottawa (PWSID IL0990800) is a community water system owned by a local government. It is regulated by the IL state drinking water program.
How many people does Ottawa serve?
Ottawa reports serving 18,097 people through 8,049 service connections in LaSalle County, Illinois.
Where does Ottawa 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 Ottawa 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 October 2025. 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 Ottawa'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 October 2025. For current results, consult the system's annual water quality report, EPA ECHO, or the IL state drinking water program.
Where can I find Ottawa's water quality report?
As a community water system, Ottawa 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 LaSalle County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Il American-Streator | LaSalle | 19,000 | Community | Surface water |
| Peru | LaSalle | 10,300 | Community | Groundwater |
| La Salle | LaSalle | 9,700 | Community | Groundwater |
| Mendota | LaSalle | 7,100 | Community | Groundwater |
| Marseilles | LaSalle | 5,061 | Community | Groundwater |
| Prairie Path Water Company-Lake Holiday | LaSalle | 4,750 | 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, “Ottawa, PWSID IL0990800, Illinois”, https://aquacensus.com/water-systems/illinois/ottawa-il0990800 (data as of October 1, 2026).