Colorado · drinking water · SDWIS through latest publish

Larkspur Town Of Water Quality — Larkspur, Colorado

PWSID CO0118030 · GroundwaterMunicipal

275 people served. 16 health-based SDWIS violations recorded in the past 5 years. 10 remain unresolved. Last cited 2 years ago.

ALL SDWIS VIOLATIONS · 20202026 (annual count)
Bar chart of annual values from 2020 to 2026, in violations. Most recent year (2026): 0 violations.60 violations'20'21'22'23'24'25'260 violations
Anomaly engine

Active signals

UNRESOLVED VIOLATION · SDWIS VIOLATION

Contaminant 4010

Unresolved Phase I/II/V Inorganic Chemical Rules violation cited in 2023 (contaminant 4010).

EPA SDWIS record

UNRESOLVED VIOLATION · SDWIS VIOLATION

Contaminant 4010

Unresolved Phase I/II/V Inorganic Chemical Rules violation cited in 2023 (contaminant 4010).

EPA SDWIS record

UNRESOLVED VIOLATION · SDWIS VIOLATION

Contaminant 4010

Unresolved Phase I/II/V Inorganic Chemical Rules violation cited in 2023 (contaminant 4010).

EPA SDWIS record

UNRESOLVED VIOLATION · SDWIS VIOLATION

Contaminant 4010

Unresolved Phase I/II/V Inorganic Chemical Rules violation cited in 2023 (contaminant 4010).

EPA SDWIS record

Most-cited contaminants

What This Utility Gets Cited For

  • Contaminant 401017 citations
  • Contaminant 75006 citations
  • Xylenes (total)2 citations
  • Benzene2 citations
  • Contaminant 29552 citations
  • Contaminant 29642 citations
Violation history

What's On The SDWIS Record

Health-based violations exceed an MCL or treatment-technique standard. Monitoring violations are reporting failures with no measured exceedance — they tell you the system isn't fully transparent, not that the water is unsafe today.

OTHER · CONTAMINANT 7500

2024 · Contaminant 7500 · Volatile Organic Chemical Rule

OTHER; returned to compliance

CONTAMINANT CODE 7500

OTHER · CONTAMINANT 7500

2024 · Contaminant 7500 · Volatile Organic Chemical Rule

OTHER; returned to compliance

CONTAMINANT CODE 7500

HEALTH-BASED · CONTAMINANT 4010UNRESOLVED

2023 · Contaminant 4010 · Phase I/II/V Inorganic Chemical Rules

Maximum contaminant level exceeded

CONTAMINANT CODE 4010

HEALTH-BASED · CONTAMINANT 4010

2023 · Contaminant 4010 · Phase I/II/V Inorganic Chemical Rules

Maximum contaminant level exceeded; returned to compliance

CONTAMINANT CODE 4010

HEALTH-BASED · CONTAMINANT 4010UNRESOLVED

2023 · Contaminant 4010 · Phase I/II/V Inorganic Chemical Rules

Maximum contaminant level exceeded

CONTAMINANT CODE 4010

HEALTH-BASED · CONTAMINANT 4010UNRESOLVED

2023 · Contaminant 4010 · Phase I/II/V Inorganic Chemical Rules

Maximum contaminant level exceeded

CONTAMINANT CODE 4010

HEALTH-BASED · CONTAMINANT 4010

2023 · Contaminant 4010 · Phase I/II/V Inorganic Chemical Rules

Maximum contaminant level exceeded; returned to compliance

CONTAMINANT CODE 4010

OTHER · CONTAMINANT 7500

2023 · Contaminant 7500 · Volatile Organic Chemical Rule

OTHER; returned to compliance

CONTAMINANT CODE 7500

OTHER · CONTAMINANT 7500

2023 · Contaminant 7500 · Volatile Organic Chemical Rule

OTHER; returned to compliance

CONTAMINANT CODE 7500

HEALTH-BASED · CONTAMINANT 4010UNRESOLVED

2023 · Contaminant 4010 · Phase I/II/V Inorganic Chemical Rules

Maximum contaminant level exceeded

CONTAMINANT CODE 4010

HEALTH-BASED · CONTAMINANT 4010

2023 · Contaminant 4010 · Phase I/II/V Inorganic Chemical Rules

Maximum contaminant level exceeded; returned to compliance

CONTAMINANT CODE 4010

HEALTH-BASED · CONTAMINANT 4010UNRESOLVED

2023 · Contaminant 4010 · Phase I/II/V Inorganic Chemical Rules

Maximum contaminant level exceeded

CONTAMINANT CODE 4010

HEALTH-BASED · CONTAMINANT 4010UNRESOLVED

2023 · Contaminant 4010 · Phase I/II/V Inorganic Chemical Rules

Maximum contaminant level exceeded

CONTAMINANT CODE 4010

HEALTH-BASED · CONTAMINANT 4010

2023 · Contaminant 4010 · Phase I/II/V Inorganic Chemical Rules

Maximum contaminant level exceeded; returned to compliance

CONTAMINANT CODE 4010

HEALTH-BASED · CONTAMINANT 4010UNRESOLVED

2023 · Contaminant 4010 · Phase I/II/V Inorganic Chemical Rules

Maximum contaminant level exceeded

CONTAMINANT CODE 4010

HEALTH-BASED · CONTAMINANT 4010UNRESOLVED

2023 · Contaminant 4010 · Phase I/II/V Inorganic Chemical Rules

Maximum contaminant level exceeded

CONTAMINANT CODE 4010

HEALTH-BASED · CONTAMINANT 4010

2023 · Contaminant 4010 · Phase I/II/V Inorganic Chemical Rules

Maximum contaminant level exceeded; returned to compliance

CONTAMINANT CODE 4010

HEALTH-BASED · CONTAMINANT 4010UNRESOLVED

2023 · Contaminant 4010 · Phase I/II/V Inorganic Chemical Rules

Maximum contaminant level exceeded

CONTAMINANT CODE 4010

HEALTH-BASED · CONTAMINANT 4010UNRESOLVED

2023 · Contaminant 4010 · Phase I/II/V Inorganic Chemical Rules

Maximum contaminant level exceeded

CONTAMINANT CODE 4010

HEALTH-BASED · CONTAMINANT 4010

2023 · Contaminant 4010 · Phase I/II/V Inorganic Chemical Rules

Maximum contaminant level exceeded; returned to compliance

CONTAMINANT CODE 4010

MONITORING · XYLENES (TOTAL)

2023 · Xylenes (total) · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2378

MONITORING · XYLENES (TOTAL)

2023 · Xylenes (total) · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2378

MONITORING · BENZENE

2023 · Benzene · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2380

MONITORING · BENZENE

2023 · Benzene · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2380

MONITORING · CONTAMINANT 2955

2023 · Contaminant 2955 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2955

MONITORING · CONTAMINANT 2955

2023 · Contaminant 2955 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2955

MONITORING · CONTAMINANT 2964

2023 · Contaminant 2964 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2964

MONITORING · CONTAMINANT 2964

2023 · Contaminant 2964 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2964

MONITORING · CONTAMINANT 2968

2023 · Contaminant 2968 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2968

MONITORING · CONTAMINANT 2968

2023 · Contaminant 2968 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2968

MONITORING · CONTAMINANT 2969

2023 · Contaminant 2969 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2969

MONITORING · CONTAMINANT 2969

2023 · Contaminant 2969 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2969

MONITORING · CONTAMINANT 2976

2023 · Contaminant 2976 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2976

MONITORING · CONTAMINANT 2976

2023 · Contaminant 2976 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2976

MONITORING · CONTAMINANT 2977

2023 · Contaminant 2977 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2977

MONITORING · CONTAMINANT 2977

2023 · Contaminant 2977 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2977

MONITORING · CONTAMINANT 2979

2023 · Contaminant 2979 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2979

MONITORING · CONTAMINANT 2979

2023 · Contaminant 2979 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2979

MONITORING · METHYL TERT-BUTYL ETHER (MTBE)

2023 · Methyl tert-butyl ether (MTBE) · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2980

MONITORING · METHYL TERT-BUTYL ETHER (MTBE)

2023 · Methyl tert-butyl ether (MTBE) · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2980

MONITORING · CONTAMINANT 2981

2023 · Contaminant 2981 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2981

MONITORING · CONTAMINANT 2981

2023 · Contaminant 2981 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2981

MONITORING · CONTAMINANT 2982

2023 · Contaminant 2982 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2982

MONITORING · CONTAMINANT 2982

2023 · Contaminant 2982 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2982

MONITORING · CONTAMINANT 2983

2023 · Contaminant 2983 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2983

MONITORING · CONTAMINANT 2983

2023 · Contaminant 2983 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2983

MONITORING · CONTAMINANT 2984

2023 · Contaminant 2984 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2984

MONITORING · CONTAMINANT 2984

2023 · Contaminant 2984 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2984

MONITORING · CONTAMINANT 2985

2023 · Contaminant 2985 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2985

MONITORING · CONTAMINANT 2985

2023 · Contaminant 2985 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2985

MONITORING · CONTAMINANT 2987

2023 · Contaminant 2987 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2987

MONITORING · CONTAMINANT 2987

2023 · Contaminant 2987 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2987

MONITORING · CONTAMINANT 2989

2023 · Contaminant 2989 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2989

MONITORING · CONTAMINANT 2989

2023 · Contaminant 2989 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2989

MONITORING · CONTAMINANT 2990

2023 · Contaminant 2990 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2990

MONITORING · CONTAMINANT 2990

2023 · Contaminant 2990 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2990

MONITORING · CONTAMINANT 2991

2023 · Contaminant 2991 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2991

MONITORING · CONTAMINANT 2991

2023 · Contaminant 2991 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2991

MONITORING · CONTAMINANT 2992

2023 · Contaminant 2992 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2992

MONITORING · CONTAMINANT 2992

2023 · Contaminant 2992 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2992

MONITORING · CONTAMINANT 2996

2023 · Contaminant 2996 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2996

MONITORING · CONTAMINANT 2996

2023 · Contaminant 2996 · Arsenic Rule

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 2996

MONITORING · CONTAMINANT 4010

2022 · Contaminant 4010 · Phase I/II/V Inorganic Chemical Rules

Failure to monitor as scheduled; returned to compliance

CONTAMINANT CODE 4010

OTHER · CONTAMINANT 7500

2020 · Contaminant 7500 · Volatile Organic Chemical Rule

OTHER; returned to compliance

CONTAMINANT CODE 7500

OTHER · CONTAMINANT 7500

2020 · Contaminant 7500 · Volatile Organic Chemical Rule

OTHER; returned to compliance

CONTAMINANT CODE 7500

Equity context · ACS 2018-2022 · USEPA-clone EJ disparity

Who Drinks This Water

Douglas County, Colorado (utility's served county per SDWIS GEOGRAPHIC_AREA — city-level not yet matched): a service population of 360,206. Local disparity score for pm2.5 (fine particulate) sits well below the reference (14). Why we surface this →

POPULATION SHARE
3.0%

Low-income

POPULATION SHARE
20.6%

People of color

POPULATION SHARE
6.5%

Under age 5

POPULATION SHARE
12.9%

Over age 64

NATIONAL PERCENTILE · vs all US block groups (population-weighted; ranked against the national EJScreen indicator distribution)

  • PM2.5 (fine particulate)Health riskFine inhalable particles 2.5 micrometers or smaller. They travel deep into the lungs and into the bloodstream — linked to asthma, heart disease, stroke, and premature death.22below the national median
  • OzoneHealth riskGround-level ozone (smog) inflames the airways. Even short exposures trigger asthma attacks and worsen chronic lung and heart disease.94in the highest 10% nationally
  • Nitrogen dioxide (NO₂)Health riskA tailpipe and combustion gas. Concentrates near busy roads and industrial sites; raises risk of airway inflammation, asthma, and lower respiratory infections in children.50near the national median
  • Diesel particulateHealth riskSoot from diesel engines (trucks, trains, ports, construction). EPA classifies it as a likely human carcinogen and a major driver of childhood asthma near freight corridors.53near the national median
  • Toxic releases (RSEI)Health riskEPA's Risk-Screening Environmental Indicators score — weights TRI chemical releases by toxicity, where they go, and how many people are nearby. Higher means greater modeled cancer and chronic-health risk.53near the national median
  • Traffic proximityHealth riskPopulation-weighted distance to high-volume roads. Living close to heavy traffic raises exposure to PM2.5, NO₂, and diesel exhaust — and the cardiovascular and asthma risks that follow.53near the national median
  • Lead-paint risk (pre-1960 housing)Health riskShare of housing built before 1960, when lead-based paint was common. Dust from deteriorating paint is the leading cause of childhood lead poisoning, which permanently impairs cognitive development.20below the national median
  • Superfund site proximityHealth riskPopulation-weighted distance to NPL Superfund sites — the most contaminated waste sites in the country. Nearby groundwater, soil, and air can carry industrial solvents, metals, and other long-lived contaminants.56near the national median
  • RMP-facility proximityHealth riskDistance to facilities holding chemicals at quantities large enough to require an EPA Risk Management Plan (refineries, fertilizer plants, etc.). These pose acute exposure risk during accidental releases.39below the national median
  • Hazardous-waste site proximityHealth riskDistance to RCRA hazardous-waste handlers (treatment, storage, disposal facilities). Indicates potential exposure to industrial chemicals in air, soil, and groundwater.15below the national median
  • Underground storage tanksHealth riskDensity of underground tanks (gasoline, heating oil, industrial fluids). Leaking tanks are a leading source of benzene and other volatile organic compounds in groundwater drinking-water supplies.53near the national median
  • NPDES wastewater proximityHealth riskDistance to permitted industrial wastewater dischargers. Closer proximity raises exposure to pollutants released into surface waters used for fishing, recreation, and downstream drinking-water intakes.88in the highest 20% nationally
  • Drinking-water non-complianceHealth riskEPA score for public water systems with health-based Safe Drinking Water Act violations. Higher means more residents on systems that recently exceeded safe limits for contaminants like lead, arsenic, or nitrate.86in the highest 20% nationally
EJ disparity scores · service-area block groups (100 = national reference; higher = greater disparate burden)
IndicatorDisparity scoreReading
PM2.5 (fine particulate)14well below the reference
Ozone50well below the reference
Nitrogen dioxide (NO₂)27well below the reference
Diesel particulate27well below the reference
Toxic releases (RSEI)26well below the reference
Traffic proximity26well below the reference
Lead-paint risk (pre-1960 housing)4well below the reference
Superfund site proximity4well below the reference
RMP-facility proximity14well below the reference
Hazardous-waste site proximity4well below the reference
Underground storage tanks20well below the reference
NPDES wastewater proximity34well below the reference
Drinking-water non-compliance28well below the reference

Source: Census ACS 2018-2022 (5-year) + USEPA-clone EJ blockgroup stats (raw indicators + EJ disparity mirror).

Source. EPA Safe Drinking Water Information System · retrieved 2026-05-07. Reporting period 2020-01-012026-05-07.

What this is not. SDWIS records compliance against federal MCLs — not a direct readout of tap-water concentrations. Active health-based violations are not the same as a current crisis; we link to the EPA record so you can verify return-to-compliance status before forming a conclusion.