Colusa County, California
5 ZIP codes · Avg score 80/100 · Grade B · Updated 2026-06-04
Within Colusa County's 5 tracked ZIP codes, safety indicators remain above the national average with few health-based violations on record.
How Colusa County Compares
How Colusa County Compares
Colusa County scores 7 points above the California state average (73/100) and 12 points above the national average (68/100).
Data: EPA SDWIS Last verified: 2026-06-04
ZIP Code Risk Map
Water Quality Map: Colusa County, California
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 12.5 (asthma 9.8%, diabetes 13.3%)
Estimated additional annual cost per homeowner: $2,332, driven primarily by flood
Infrastructure: 0.342% avg pipe failure probability, 20% of ZIPs at high risk
64.2% of homes built before 1978 (lead paint era)
Violation History (2021–2024)
↑ Worsening trendEPA violation counts by year across Colusa County water systems. Health-based shown in red, total in blue.
Peak year: 2024 with 5 violations. Past 5 years: 16 total (16 health-based). Health-based violations are rising versus the prior 2-year window — worth closer monitoring.
Source: EPA SDWIS historical violations. Data may lag 6–12 months for the most recent year.
County Health Indicators vs National Average
Black markers indicate national averages. Source: CDC PLACES, Census ACS.
Infrastructure Overview
Sources: Census ACS (housing age), EPA SDWIS (infrastructure risk model), state bridge inspection data.
Compound Risk Breakdown
Estimated additional annual cost per homeowner: $2,332
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
7,687 housing units in Colusa County
Source: U.S. Census Bureau ACS B25034 (Year Structure Built).
Water Safety Affordability
How much it costs to fix water issues relative to home values in Colusa County
Remediation costs are relatively manageable for most homeowners in Colusa County, representing a small fraction of property value.
Remediation includes water filtration, lead abatement, radon mitigation, and flood protection where applicable. Source: Census ACS, EPA SDWIS.
Health Outcomes vs National Average
CDC PLACES data for Colusa County residents
Black markers = national averages. Red = above national avg. Green = below. Source: CDC PLACES, Census ACS.
Water Systems with Most Violations
Top 5 systems in Colusa County ranked by EPA violation count.
| # | Water System | Population | Violations |
|---|---|---|---|
| 1 | City of Colusa | 6,447 | 9 |
| 2 | City of Williams | 5,538 | 4 |
| 3 | Arbuckle Public Utility District | 2,778 | 4 |
| 4 | Cedar Creek Mobilehome Park | 40 | 4 |
| 5 | Maxwell Public Utility District | 1,175 | 1 |
7 total water systems serve Colusa County.
All ZIP Codes in Colusa County
5 ZIP codes tracked in Colusa County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 95912 | Arbuckle | 90 | A | 4 | $425K |
| 2 | 95955 | Maxwell | 88 | A | 1 | $289K |
| 3 | 95987 | Williams | 82 | B | 0 | $372K |
| 4 | 95932 | Colusa | 77 | B | 4 (1 health) | $367K |
| 5 | 95957 | Meridian | 65 | C | 0 | $296K |
Recommended Buyer Guides for Colusa County
While many sites publish identical guide lists across every county they cover, the selection here changes by location — driven by the EPA, NSF, FEMA, and CDC datasets that describe the actual conditions documented for this jurisdiction in the federal record.
- Best Lead Paint Test Kits — 64.2% of homes built before 1978
- Best Sump Pumps — Flood is the top compound risk factor
- Best Mold Test Kits — Flood-driven moisture and mold risk
Deep Dive Reports
Detailed analysis for Colusa County, California
Overview
Colusa County in California covers 5 ZIP codes with an average Home Safety Score of B (80/100).
3 of 5 ZIP codes have recorded EPA violations. 1 health-based violation have been documented.
← Back to California water quality report
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Home values: U.S. Census Bureau ACS (median estimates by ZCTA)
Updated daily.