CONGRESSIONAL DISTRICT CA

California - 4th District

119th Congress · 70 ZIP codes · Avg score 95/100 · Grade A · Updated N/A

Data: EPA SDWIS / Census 119th Congress Last verified: N/A

ZipCheckup's versioned Home Safety Profile covers 70 ZIP codes in California's 4th District: the measured model 4.0.0 average is Grade A (95/100). 89 EPA violations on record, 41 health-based.

A
District Grade
95
Avg Safety Score
70
ZIP Codes
89
Total Violations
41
Health Violations
68
Water Systems
Best ZIP: 94571 (100/100)
Lowest ZIP: 95476 (69/100)

Top Contaminants

Stage 2 DBP Rule (27) Consumer Confidence Report Rule (17) Haloacetic Acids (HAA5) (14) Total Trihalomethanes (TTHM) (13) Stage 1 DBP Rule (10)

ZIP Codes in This District

70 ZIP codes tracked in California's 4th District. Showing top 50 by safety score.

# ZIP Code City Safety Score Grade Violations
1 94571 Rio Vista 100 A 0
2 94589 Vallejo 100 A 0
3 95401 Santa Rosa 100 A 0
4 95451 Kelseyville 100 A 0
5 95458 Lucerne 100 A 0
6 95464 Nice 100 A 0
7 95467 Hidden Valley Lake 100 A 0
8 95616 Davis 100 A 1
9 95620 Dixon 100 A 0
10 95694 Winters 100 A 0
11 95695 Woodland 100 A 0
12 94931 Cotati 99 A 2
13 95407 Santa Rosa 99 A 2
14 95618 Davis 99 A 3
15 95776 Woodland 99 A 3
16 95422 Clearlake 97 A 4 (4 health)
17 95453 Lakeport 96 A 3 (1 health)
18 95405 Santa Rosa 95 A 3 (2 health)
19 95409 Santa Rosa 95 A 3 (1 health)
20 95404 Santa Rosa 89 A 11 (3 health)
21 95442 Glen Ellen 83 B 0
22 95687 Vacaville 83 B 0
23 95688 Vacaville 83 B 0
24 94928 Rohnert Park 81 B 4
25 95476 Sonoma 69 C 9 (3 health)
26 94503 American Canyon N/A N/A 2 (1 health)
27 94508 Angwin N/A N/A 2 (2 health)
28 94512 Birds Landing N/A N/A 0
29 94515 Calistoga N/A N/A 6 (5 health)
30 94558 Napa N/A N/A 2
31 94559 Napa N/A N/A 0
32 94562 Oakville N/A N/A N/A
33 94567 Pope Valley N/A N/A 2 (2 health)
34 94573 Rutherford N/A N/A N/A
35 94574 Saint Helena N/A N/A 9 (8 health)
36 94576 Deer Park N/A N/A 2 (2 health)
37 94581 Napa N/A N/A N/A
38 94599 Yountville N/A N/A 3 (1 health)
39 94926 Rohnert Park N/A N/A N/A
40 94927 Rohnert Park N/A N/A N/A
41 94951 Penngrove N/A N/A 2
42 95402 Santa Rosa N/A N/A N/A
43 95406 Santa Rosa N/A N/A N/A
44 95416 Boyes Hot Springs N/A N/A N/A
45 95423 Clearlake Oaks N/A N/A 4 (4 health)
46 95424 Clearlake Park N/A N/A N/A
47 95426 Cobb N/A N/A 3 (1 health)
48 95431 Eldridge N/A N/A N/A
49 95433 El Verano N/A N/A N/A
50 95435 Finley N/A N/A N/A

Overview

California's 4th District encompasses 70 ZIP codes tracked by ZipCheckup. The district's average Home Safety Score is A (95/100).

89 EPA violations have been recorded across this district's water systems. 41 are health-based violations. About 57% of the 44 ZIP records with a reported violation count have at least one violation.

Top Contaminants

The most frequently cited water quality issues in this district:

  • Stage 2 DBP Rule - 27 violations
  • Consumer Confidence Report Rule - 17 violations
  • Haloacetic Acids (HAA5) - 14 violations
  • Total Trihalomethanes (TTHM) - 13 violations
  • Stage 1 DBP Rule - 10 violations

Housing Context

Homes in this district were built on average around 1975 (~51 years old). Older homes may have lead pipes or solder - consider a water filter if your home predates 1986.

Data Sources

Updated daily. Data covers 70 ZIP codes in California's 4th District.

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How to cite this page

APA ZipCheckup. (2026). California 4th District: 89 EPA Violations - A. https://zipcheckup.com/congressional/ca-4/
BibTeX
@misc{zipcheckup-congressional-ca-4,
  author = {{ZipCheckup}},
  title  = {{California 4th District: 89 EPA Violations - A}},
  year   = {2026},
  url    = {https://zipcheckup.com/congressional/ca-4/}
}

Page version: August 2026.

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