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County water report

Lassen County Water Report

Drinking-water compliance, watershed health, monitoring records, and river conditions for Lassen County, California.

Water grade

C

Water score

54.6

State rank

#19

of 58

Health violations

2

EPA SDWIS, 5-year lookback

Watershed impaired

22.9%

70 water bodies assessed

Monitoring sites

34

4,168 recent measurements

Live streamflow

No gauge

PIT R BYPSS FLW BL DIV TO MUCK VALLEY PP NR BIEBER

Water at a glance

Key Water Indicators for Lassen County

EPA SDWIS

Safety Grade

C

Score: 54.6 / 100

EPA SDWIS

Active Violations

2

5-year health-based lookback

EPA ATTAINS

Watershed Health

23% impaired

70 bodies assessed

USGS NWIS

Streamflow Snapshot

No gauge

PIT R BYPSS FLW BL DIV TO MUCK VALLEY PP NR BIEBER

EPA WQP

Monitoring Sites

34

4,168 recent readings

Source: EPA SDWIS · Safe Drinking Water Information System

Drinking Water Compliance

Compliance grade

C

Based on EPA SDWIS compliance history.

Water score

Higher scores indicate cleaner recent compliance records.

54.6/100

Health violations

2

Health-based violations

Violations per 100K served

10.7

Population-normalized SDWIS rate

Editorial analysis

Understanding Lassen County’s Water

Drinking Water Quality Overview

EPA SDWIS

Lassen County's drinking water earned a C grade, scoring 54.6 out of 100. Over the past five years, EPA SDWIS records 2 health-based violations — a small cluster that warrants attention.

Watershed Conditions

EPA ATTAINS

Under the Clean Water Act §303(d), EPA ATTAINS tracks whether waterways meet quality standards for drinking, recreation, and aquatic life (reporting cycle: 2022). A notable 22.9% of assessed waterways carry an impairment designation (16 of 70 water bodies) across Lassen County's watersheds. The leading impairment causes are pathogens and nitrogen. Impairment does not mean tap water is unsafe — it measures ambient waterway conditions upstream of treatment, not finished drinking water.

Monitoring Network

EPA WQP

EPA's Water Quality Portal (WQP) aggregates monitoring data from federal, state, and tribal agencies. Lassen County has moderate coverage with 34 active monitoring sites with 4,168 recent measurements on record. Predominant monitoring categories include physical and inorganics, minor, metals. More monitoring sites generally indicate greater scientific attention to local water conditions — and provide the baseline data that regulators use to set future impairment listings.

Editorial advisory

What the data suggests for Lassen County

Water Verdict

Lassen County receives a below-average water quality assessment with a grade of C and a score of 54.6 out of 100. Residents should review their utility's Consumer Confidence Report and may want to consider additional water filtration for drinking.

Violation Context

Lassen County has recorded 2 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 10.7 violations per 100,000 people served, this rate is high and signals significant water quality management issues.

Consumer Guidance

Tap water in Lassen County meets baseline standards but the compliance record shows room for improvement, with a Grade C rating. Lassen County's drinking-water compliance score is 54.6 out of 100. The violation rate for Lassen County is 10.7 per 100,000 people served. Residents who are immunocompromised, pregnant, or have young children may benefit from using an NSF 53-certified filter. Contacting your local utility for the current Consumer Confidence Report will confirm which specific violations were recorded and whether they have been resolved. Pathogens is the leading impairment cause in Lassen County's watershed. With 34 active water-quality monitoring sites in Lassen County, data coverage is strong. A pipeline streamflow snapshot from the PIT R BYPSS FLW BL DIV TO MUCK VALLEY PP gauge is also available on this page.

Regional Context

Lassen County has better water quality than the average county in California. Its water score is 10 points higher than the state average, indicating stronger water system performance relative to neighboring counties.

Advisory text summarizes county-level public records and is not a replacement for your utility's current Consumer Confidence Report or direct local notices.

Contaminants & Resources

Key issues flagged in Lassen County's water environment

Watershed Impairment Causes (EPA ATTAINS)

  • 1

    Pathogens

    Impairment cause per EPA Clean Water Act §303(d) assessment

  • 2

    Nitrogen

    Impairment cause per EPA Clean Water Act §303(d) assessment

  • 3

    Total Dissolved Solids (Tds)

    Impairment cause per EPA Clean Water Act §303(d) assessment

Source: EPA ATTAINS · Reporting cycle 2022

Official EPA Resources for Lassen County

EPA How's My Waterway

Interactive watershed health data for Lassen County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Lassen County

Consumer Confidence Reports (CA)

Annual water quality reports from utilities in California

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

22.9%

16 of 70 assessed

Some impairment

Top Impairment Causes

  • 1

    PATHOGENS

  • 2

    NITROGEN

  • 3

    TOTAL DISSOLVED SOLIDS (TDS)

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

34

Active in the past 5 years

Measurements Recorded

4.2K

4,168 total readings

Most Measured

  • Physical
  • Inorganics, Minor, Metals
  • Nutrient

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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Water Cost Estimate

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Annual Total

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Monthly

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Water Bill

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Filter Cost

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Safety Grade for Lassen County:C — Moderate

Some violations or watershed impairment detected.

Estimates use the national average residential water rate ($0.0068/gal, EPA/AWWA 2023) and EPA WaterSense per-person consumption baseline (75 gal/person/day). Actual bills vary by utility, usage tier, and local infrastructure fees. For informational purposes only.

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Frequently Asked Questions

What is the water quality in Lassen County, California?
Lassen County, California has a drinking-water quality grade of C with a score of 54.6/100, based on EPA SDWIS compliance data. The county has 2 health-based drinking water violations over the past 5 years. Watershed health, monitoring records, and streamflow snapshots are reported separately on this page.
Are there any water violations in Lassen County?
Lassen County has 2 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 Lassen County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 22.9% of Lassen County's 70 assessed water bodies are classified as impaired (16 impaired). The top reported causes are PATHOGENS, NITROGEN, TOTAL DISSOLVED SOLIDS (TDS). 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 Lassen County?
EPA's Water Quality Portal records 4,168 measurements from 34 monitoring sites in Lassen County over the past five years. The most frequently measured characteristic groups are Physical, Inorganics, Minor, Metals, Nutrient. 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 Lassen County water compare to the California average?
Lassen County's SDWIS water quality score of 54.6/100 is higher 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 Lassen County?
Based on EPA SDWIS data, Lassen County has a water quality grade of C (54.6/100). This indicates moderate compliance. Some violations have been recorded but overall standards are maintained. 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).
Does Lassen County have clean drinking water?
Lassen County has 2 health-based drinking water violations according to EPA records. With a water quality score of 54.6/100 and grade C, the county's drinking water has had some compliance issues but continues to be monitored. Note: drinking-water compliance speaks to the public water system, not necessarily to the watershed itself — check the Watershed Health zone for ATTAINS §303(d) data.
How does Lassen County rank for water quality in California?
Lassen County ranks #19 out of 58 counties in California by SDWIS water quality score (1 = best). With a score of 54.6/100, it falls in the top 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

San Diego County

California

C

54.6

Water score

Humboldt County

California

C

54.8

Water score

Fresno County

California

C

52.5

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 and 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 Evan Brooks, Data EditorUpdated Reviewed by Evan Brooks, Data Editor

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