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EPA SDWIS

Madera County Water Quality

Madera County, California

Water Grade

F

Water Score

8.8

Violations

519

State Rank

#58

of 58 (1 = best)

EPA SDWIS Compliance

Drinking Water Quality

Water Quality Grade

F

Based on EPA compliance history and violation data

Water Score

8.8/100

Higher = better quality

Health Violations

519

Health-based violations

Violation Rate

385.0%

Systems with violations

Water Advisory: Madera County

Water Verdict

Madera County receives a poor water quality assessment with a grade of F and a score of 8.8 out of 100. The water supply has documented quality issues. Residents are strongly encouraged to use filtered or bottled water for drinking and to stay informed about utility improvement plans.

Violation Context

Madera County has recorded 519 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 385.0 violations per 1,000 residents, this rate is high and signals significant water quality management issues.

Consumer Guidance

Residents of Madera County are advised to use filtered or bottled water for drinking and cooking until water quality improves. A reverse-osmosis or activated-carbon filter certified to remove the contaminants listed in the utility's Consumer Confidence Report is recommended. With 519 recorded health violations, staying informed about utility communications and boil-water notices is especially important. For long-term peace of mind, request your utility's latest Consumer Confidence Report and consider independent water testing if you have specific health concerns.

Regional Context

Madera County has poorer water quality than the average county in California. Its water score is 35.8 points lower than the state average, suggesting more challenges with contamination control or infrastructure than neighboring counties.

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

28.6%

14 of 49 assessed

Some impairment

Top Impairment Causes

  • 1

    PH

  • 2

    MERCURY

  • 3

    DISSOLVED OXYGEN

Source: EPA ATTAINS · Reporting cycle 2022

Impairment is determined under the Clean Water Act §303(d): a water body is impaired when it fails to meet state-defined quality standards for designated uses (drinking, recreation, aquatic life). Assessment coverage varies by state — counties without assessed water bodies are not shown.

Past 5 years

Water Quality Monitoring

Monitoring Sites

25

Active in the past 5 years

Measurements Recorded

2.7K

2,724 total readings

Most Measured

  • Organics, Other
  • Organics, Pesticide
  • Physical

Categories measured most frequently

Data from the EPA Water Quality Portal (WQP), aggregating monitoring records from federal, state, and tribal sources. Each measurement represents a single sample analyzed for a specific characteristic (e.g., E. coli, pH, dissolved oxygen, nitrogen).

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Frequently Asked Questions

What is the water quality in Madera County, California?
Madera County, California has a drinking-water quality grade of F with a score of 8.8/100, based on EPA SDWIS compliance data. The county has 519 health-based drinking water violations over the past 5 years. Watershed health, monitoring records, and live streamflow are reported separately on this page.
Are there any water violations in Madera County?
Madera County has 519 health-based drinking water violations recorded by the EPA over the past 5 years. Health-based violations indicate instances where contaminant levels exceeded EPA Maximum Contaminant Levels (MCLs). Violations may have been resolved — check with your local water utility for current status.
How healthy are the watersheds in Madera County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 28.6% of Madera County's 49 assessed water bodies are classified as impaired (14 impaired). The top reported causes are PH, MERCURY, DISSOLVED OXYGEN. Impairment means the water body fails to meet state quality standards for at least one designated use — drinking water source, recreation, aquatic life, or fish consumption. Note: watershed impairment doesn't always translate to tap-water issues; treatment plants can remove most regulated contaminants.
How much water-quality monitoring happens in Madera County?
EPA's Water Quality Portal records 2,724 measurements from 25 monitoring sites in Madera County over the past five years. The most frequently measured characteristic groups are Organics, Other, Organics, Pesticide, Physical. Each measurement is a single sample analyzed for one characteristic (E. coli, pH, dissolved oxygen, etc.). High monitoring density means more scientific evidence behind any reported signal — it does not by itself indicate water quality.
How does Madera County water compare to the California average?
Madera County's SDWIS water quality score of 8.8/100 is lower than the California state average of 44.6. The average water quality grade across California is D, based on data from 58 counties with available SDWIS data.
Is tap water safe to drink in Madera County?
Based on EPA SDWIS data, Madera County has a water quality grade of F (8.8/100). This indicates below-average compliance with significant violations. Residents may want to consider home water filtration or independent testing. The grade speaks to the public water system, not the watershed — for watershed-level concerns, see the Watershed Health zone. For the most up-to-date information, contact your local water utility or review your Consumer Confidence Report (CCR).
Why does Madera County have so many water violations?
Madera County has 519 health-based drinking water violations on record from the EPA SDWIS database. A higher violation count can result from aging infrastructure, underfunded water utilities, agricultural runoff contamination, or industrial pollution. Counties with more water systems may also see more violations simply due to scale. Residents concerned about water quality should consider independent water testing and home filtration systems.
How does Madera County rank for water quality in California?
Madera County ranks #58 out of 58 counties in California by SDWIS water quality score (1 = best). With a score of 8.8/100, it falls in the bottom third of counties statewide. The ranking reflects EPA SDWIS compliance only — not watershed impairment, monitoring density, or streamflow, which are tracked separately on this page.

Counties with Similar Water Quality

Colusa County

California

F

13.1

Water score

Alpine County

California

F

13.8

Water score

Tehama County

California

F

15.7

Water score

Data Sources

Drinking-water compliance data from the EPA Safe Drinking Water Information System (SDWIS) via the ECHO enforcement database. Scores reflect compliance history and health-based violation counts.

Watershed health and impaired-waterway data from the EPA ATTAINS Clean Water Act §303(d) assessments — state-reported, EPA-finalized.

Water-quality monitoring counts from the EPA Water Quality Portal (WQP) — federated USGS, EPA, and state agency sampling records over a rolling 5-year window.

Disclaimer: This data is informational only. It is not health, legal, or professional advice. For concerns about your specific water supply, contact your local water utility.

By Logan Johnson, Founder & Data EditorUpdated Reviewed by Logan Johnson, Founder & Data Editor

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