Public water system record
Oswego
Serves Oswego and Boulder Hill, Kendall County, IL · 38,169 people served
Federal records show 1 health-based violation and 4 monitoring/reporting issues for Oswego in the last ten years. The most serious issue in this window was a resolved Combined Radium (-226 and -228) violation.
System profile
- Health-based violations, last 10 years
- 1
- Resolved
- 1
- Unresolved
- 0
- Any acute record
- No
- Monitoring issues, last 10 years
- 4
Key facts
- Oswego draws water from 8 wells.
- Highest measured level in the last 10 years: Combined Radium (-226 and -228), 6 pCi/L, federal limit 5 pCi/L (1.2 times the limit), 2017.
- Most recent formal enforcement: signed compliance agreement by Illinois, January 2004.
- Record on file since 1977, with 23 health-based violations before October 19, 2016.
- Lead pipe inventory: 0 lead and 0 unknown out of 12,051 service lines.
Check whether Oswego serves your address
Health-based violations
Since October 2016Violation data reflects EPA records through March 2026. For the most current status, visit the EPA ECHO database.
| Contaminant | Rule family | Start date | Status | Acute |
|---|---|---|---|---|
|
Combined Radium (-226 and -228)
Contaminant limit exceeded
Measured 6 pCi/L, federal limit 5 pCi/L (1.2 times the limit)
|
340 | Jan 1, 2017 | Resolved | No |
Monitoring and reporting issues
Since October 2016Missed tests or reports, not contaminants found above a limit.
| Issue | Start date | Status |
|---|---|---|
|
Chlorine
Monitoring and reporting
|
Sep 1, 2024 | Resolved |
|
Consumer Confidence Rule
OTHER
|
Jul 1, 2022 | Resolved |
|
Consumer Confidence Rule
OTHER
|
Jul 1, 2017 | Resolved |
|
Public Notice
OTHER
|
May 14, 2017 | Resolved |
Full record since 1977
EPA's records for Oswego go back to 1977. Before October 19, 2016 they list 23 health-based violations (23 resolved) and 28 monitoring or reporting violations.
| Violations that began in | Health-based | Monitoring and reporting |
|---|---|---|
| 1970s | 0 | 1 |
| 1980s | 1 | 0 |
| 1990s | 4 | 22 |
| 2000s | 18 | 2 |
| 2010 to October 18, 2016 | 0 | 3 |
| October 19, 2016 to 2019 | 1 | 2 |
| 2020s | 0 | 2 |
Most recent health-based violation before October 19, 2016: Combined Radium (-226 and -228), began April 2006, Resolved.
Show all 23 health-based violations before October 19, 2016
| Contaminant | Start date | Status |
|---|---|---|
|
Combined Radium (-226 and -228)
Contaminant limit exceeded
Measured 7 pCi/L, federal limit 5 pCi/L (1.4 times the limit)
|
Apr 1, 2006 | Resolved |
|
Combined Radium (-226 and -228)
Contaminant limit exceeded
Measured 7 pCi/L, federal limit 5 pCi/L (1.4 times the limit)
|
Jan 1, 2006 | Resolved |
|
Combined Radium (-226 and -228)
Contaminant limit exceeded
|
Oct 1, 2005 | Resolved |
|
Combined Radium (-226 and -228)
Contaminant limit exceeded
|
Jul 1, 2005 | Resolved |
|
Combined Radium (-226 and -228)
Contaminant limit exceeded
|
Apr 1, 2005 | Resolved |
|
Combined Radium (-226 and -228)
Contaminant limit exceeded
|
Jan 1, 2005 | Resolved |
|
Gross Alpha, Excl. Radon and U
Contaminant limit exceeded
|
Jan 1, 2005 | Resolved |
|
Combined Radium (-226 and -228)
Contaminant limit exceeded
|
Oct 1, 2004 | Resolved |
|
Total Coliform
Contaminant limit exceeded
|
Aug 1, 2004 | Resolved |
|
Combined Radium (-226 and -228)
Contaminant limit exceeded
|
Jul 1, 2004 | Resolved |
|
Combined Radium (-226 and -228)
Contaminant limit exceeded
|
Apr 1, 2004 | Resolved |
|
Combined Radium (-226 and -228)
Contaminant limit exceeded
|
Jan 1, 2004 | Resolved |
|
Combined Radium (-226 and -228)
Contaminant limit exceeded
|
Oct 1, 2003 | Resolved |
|
Combined Radium (-226 and -228)
Contaminant limit exceeded
|
Jul 1, 2003 | Resolved |
|
Combined Radium (-226 and -228)
Contaminant limit exceeded
|
Apr 1, 2003 | Resolved |
|
Combined Radium (-226 and -228)
Contaminant limit exceeded
|
Jan 1, 2003 | Resolved |
|
Combined Radium (-226 and -228)
Contaminant limit exceeded
|
Oct 1, 2002 | Resolved |
|
Gross Alpha, Excl. Radon and U
Contaminant limit exceeded
|
Mar 31, 2001 | Resolved |
|
Combined Radium (-226 and -228)
Contaminant limit exceeded
|
Feb 1, 1999 | Resolved |
|
Combined Radium (-226 and -228)
Contaminant limit exceeded
|
Mar 1, 1995 | Resolved |
|
Combined Radium (-226 and -228)
Contaminant limit exceeded
|
Feb 1, 1995 | Resolved |
|
Combined Radium (-226 and -228)
Contaminant limit exceeded
|
Feb 25, 1991 | Resolved |
|
Combined Radium (-226 and -228)
Contaminant limit exceeded
|
Apr 1, 1984 | Resolved |
Enforcement actions
Illinois regulators took 4 formal enforcement actions against Oswego between 1991 and 2004. The most recent was a signed compliance agreement in January 2004.
| Date | By | Action | Violations covered |
|---|---|---|---|
| Jan 23, 2004 | Illinois | Signed compliance agreement | 20 violations (20 health-based): Combined Radium (-226 and -228), Gross Alpha, Excl. Radon and U |
| Dec 20, 2001 | Illinois | Signed compliance agreement | 7 violations (7 health-based): Combined Radium (-226 and -228), Gross Alpha, Excl. Radon and U |
| Feb 28, 2000 | Illinois | Signed compliance agreement | 1 violation: Consumer Confidence Rule |
| Oct 10, 1991 | Illinois | Compliance order (no penalty) | 1 violation (1 health-based): Combined Radium (-226 and -228) |
What the violations mean
Combined Radium (-226 and -228)
1 incidentTest results for Combined Radium (-226 and -228) were above the federal limit (a maximum contaminant level violation).
The utility had to notify customers about this violation.
Where the water comes from
Oswego draws water from 8 wells. 3 smaller public systems such as schools, businesses or campgrounds buy water from Oswego.
Annual water quality report
Oswego must give its customers an annual water quality report (Consumer Confidence Report) by July 1, with the levels its tests found in the previous year.
Systems serving 10,000 or more people must mail or deliver the report to every customer, and from 2027 they must send it twice a year.
Find a posted report with EPA's Consumer Confidence Report search
Testing your own water
To test the water at your tap, or a private well this record does not cover, use a laboratory certified for drinking water by Illinois.
Certified drinking water labs by state EPA guidance for private wells