waterbycounty
EPA SDWIS

McMullen County Water Quality

McMullen County, Texas

Water Grade

F

Water Score

10.1

Violations

3

State Rank

#183

of 254 (1 = best)

EPA SDWIS Compliance

Drinking Water Quality

Water Quality Grade

F

Based on EPA compliance history and violation data

Water Score

10.1/100

Higher = better quality

Health Violations

3

Health-based violations

Violation Rate

326.8%

Systems with violations

Water Advisory: McMullen County

Water Verdict

McMullen County receives a poor water quality assessment with a grade of F and a score of 10.1 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

McMullen County has recorded 3 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 326.8 violations per 1,000 residents, this rate is high and signals significant water quality management issues.

Consumer Guidance

Residents of McMullen 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 3 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

McMullen County has poorer water quality than the average county in Texas. Its water score is 20.3 points lower than the state average, suggesting more challenges with contamination control or infrastructure than neighboring counties.

Past 5 years

Water Quality Monitoring

Monitoring Sites

6

Active in the past 5 years

Measurements Recorded

1.9K

1,884 total readings

Most Measured

  • Physical
  • Inorganics, Major, Non-metals
  • Organics, Other

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).

Live USGS Streamgage

River & Stream Conditions

Current Discharge

0.00cfs

May 14, 6:30 PM UTC

vs Long-Term Average

0%

Well below typical

Primary Streamgage

Nueces Rv nr Tilden, TX

USGS site
08194500
Drainage area
8,093 sq mi
Long-term mean
346 cfs

One representative streamgage (the one with the largest drainage area in the county). Many counties have multiple gauges — this view summarizes the primary one. The long-term mean is the full-record annual average; "% of typical" compares the latest reading against that average.

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Frequently Asked Questions

What is the water quality in McMullen County, Texas?
McMullen County, Texas has a drinking-water quality grade of F with a score of 10.1/100, based on EPA SDWIS compliance data. The county has 3 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 McMullen County?
McMullen County has 3 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 much water-quality monitoring happens in McMullen County?
EPA's Water Quality Portal records 1,884 measurements from 6 monitoring sites in McMullen County over the past five years. The most frequently measured characteristic groups are Physical, Inorganics, Major, Non-metals, Organics, Other. 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.
What's happening with rivers in McMullen County right now?
McMullen County's primary USGS streamgage on the Nueces Rv is currently reading 0 cubic feet per second — 0% of the long-term mean of 345.64 cfs. This is well below typical — often a signal of drought stress on source water. For genuine real-time data, visit waterdata.usgs.gov.
How does McMullen County water compare to the Texas average?
McMullen County's SDWIS water quality score of 10.1/100 is lower than the Texas state average of 30.4. The average water quality grade across Texas is F, based on data from 254 counties with available SDWIS data.
Is tap water safe to drink in McMullen County?
Based on EPA SDWIS data, McMullen County has a water quality grade of F (10.1/100). 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).
Does McMullen County have clean drinking water?
McMullen County has 3 health-based drinking water violations according to EPA records. With a water quality score of 10.1/100 and grade F, 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 McMullen County rank for water quality in Texas?
McMullen County ranks #183 out of 254 counties in Texas by SDWIS water quality score (1 = best). With a score of 10.1/100, 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

Zapata County

Texas

F

10.1

Water score

Blanco County

Texas

F

10.2

Water score

Cass County

Texas

F

10.2

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.

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.

Live streamflow from the USGS National Water Information System (NWIS) — continuous discharge measurements from the largest-drainage gauge in each county, compared against the full-record long-term annual mean.

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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