Willow County Water District

Published drinking-water records and contacts for Willow County Water District. System CA2310005. Review sources and dates; not a real-time water assessment.

System ID: CA2310005
State or territory: CA
Published population served: 3797
System type (source code): CWS

Published records and dates

PFAS / lithium (EPA UCMR 5): 60 — 2023-02-15 – 2023-08-08
Lead and copper monitoring summaries: 32 — 1992-01-01 – 2025-12-31

Missing records here do not mean the provider did not test. Published records are not a real-time assessment of your tap water.

Published testing results

Selected recent records are shown below. Different sampling locations and dates are not interchangeable. These excerpts are not a complete testing history.

“<” means below the stated reporting limit, not zero. A reported measurement alone is not a safety verdict. Read an example

EPA UCMR 5 — most recent imported sample per substance
Substance	Published result	Reporting limit	Sample date	Sampling location
11Cl-PF3OUdS	< 0.005 µg/L	0.005 µg/L	2023-08-08	Well Field / EP1
4:2 FTS	< 0.003 µg/L	0.003 µg/L	2023-08-08	Well Field / EP1
6:2 FTS	< 0.005 µg/L	0.005 µg/L	2023-08-08	Well Field / EP1
8:2 FTS	< 0.005 µg/L	0.005 µg/L	2023-08-08	Well Field / EP1
9Cl-PF3ONS	< 0.002 µg/L	0.002 µg/L	2023-08-08	Well Field / EP1
ADONA	< 0.003 µg/L	0.003 µg/L	2023-08-08	Well Field / EP1
HFPO-DA	< 0.005 µg/L	0.005 µg/L	2023-08-08	Well Field / EP1
NEtFOSAA	< 0.005 µg/L	0.005 µg/L	2023-08-08	Well Field / EP1
NFDHA	< 0.02 µg/L	0.02 µg/L	2023-08-08	Well Field / EP1
NMeFOSAA	< 0.006 µg/L	0.006 µg/L	2023-08-08	Well Field / EP1
PFBA	< 0.005 µg/L	0.005 µg/L	2023-08-08	Well Field / EP1
PFBS	< 0.003 µg/L	0.003 µg/L	2023-08-08	Well Field / EP1
PFDA	< 0.003 µg/L	0.003 µg/L	2023-08-08	Well Field / EP1
PFDoA	< 0.003 µg/L	0.003 µg/L	2023-08-08	Well Field / EP1
PFEESA	< 0.003 µg/L	0.003 µg/L	2023-08-08	Well Field / EP1
PFHpA	< 0.003 µg/L	0.003 µg/L	2023-08-08	Well Field / EP1
PFHpS	< 0.003 µg/L	0.003 µg/L	2023-08-08	Well Field / EP1
PFHxA	< 0.003 µg/L	0.003 µg/L	2023-08-08	Well Field / EP1
PFHxS	< 0.003 µg/L	0.003 µg/L	2023-08-08	Well Field / EP1
PFMBA	< 0.003 µg/L	0.003 µg/L	2023-08-08	Well Field / EP1
PFMPA	< 0.004 µg/L	0.004 µg/L	2023-08-08	Well Field / EP1
PFNA	< 0.004 µg/L	0.004 µg/L	2023-08-08	Well Field / EP1
PFOA	< 0.004 µg/L	0.004 µg/L	2023-08-08	Well Field / EP1
PFOS	< 0.004 µg/L	0.004 µg/L	2023-08-08	Well Field / EP1
PFPeA	< 0.003 µg/L	0.003 µg/L	2023-08-08	Well Field / EP1
PFPeS	< 0.004 µg/L	0.004 µg/L	2023-08-08	Well Field / EP1
PFTA	< 0.008 µg/L	0.008 µg/L	2023-08-08	Well Field / EP1
PFTrDA	< 0.007 µg/L	0.007 µg/L	2023-08-08	Well Field / EP1
PFUnA	< 0.002 µg/L	0.002 µg/L	2023-08-08	Well Field / EP1
lithium	< 9 µg/L	9 µg/L	2023-08-08	Well Field / EP1

Download all EPA UCMR 5 records (CSV)

Lead and copper: 90th-percentile summaries

These describe a monitoring period across sampled locations, not the result at your home. How to read the 90th percentile

Eight most recent imported monitoring summaries
Substance	Published 90th percentile	Monitoring period	Source quarter
Lead (PB90)	0 mg/L	2025-01-01 – 2025-12-31	2026Q3
Lead (PB90)	0 mg/L	2024-07-01 – 2024-12-31	2026Q3
Lead (PB90)	0 mg/L	2024-01-01 – 2024-06-30	2026Q3
Lead (PB90)	0.0052 mg/L	2021-01-01 – 2023-12-31	2026Q3
Copper (CU90)	1.5 mg/L	2021-01-01 – 2023-12-31	2026Q3
Lead (PB90)	0 mg/L	2018-01-01 – 2020-12-31	2026Q3
Lead (PB90)	0 mg/L	2015-01-01 – 2017-12-31	2026Q3
Lead (PB90)	0 mg/L	2012-01-01 – 2014-12-31	2026Q3

Published compliance history

3 imported records. Status is as recorded in the source; historical records are not current advisories. Missing records do not establish that no violations occurred.

Twenty most recent imported compliance records
Rule / record	Period	Recorded status	Health-based (EPA classification)	Source quarter
Revised Total Coliform Rule / Monitoring, Routine (RTCR)	2024-08-01 – 2024-08-31	Archived	No	2026Q3
Ground Water Rule / Failure to Conduct Assessment Monitoring	2021-01-01 – 2021-01-31	Resolved	No	2026Q3
Miscellaneous Other Rules / Notification, Public	1988-10-01 – 1988-10-31	Archived	No	2026Q3

Source dates and refresh checks

A refresh check is not a sample date. Publication periods, sample dates and checks are shown separately.

EPA SDWIS lead/copper summaries and service areas — source period: — – —; last checked: 2026-10-17
EPA SDWIS contacts and compliance records — source period: — – —; last checked: 2026-10-17
EPA UCMR 5 sample results — source period: 2023-01-03 – 2026-06-17; last checked: 2026-10-17

Administrative contact (EPA filing)

Walker, Jared: 707-462-2666

An administrative filing contact may not be a customer-service line. Confirm current contact details with the provider.

Official state resources · How to read these records