waterbycounty
Compiled federal source snapshot

Louisiana Water Quality

Drinking water data for all 63 counties.

Avg SDWIS Compliance Index

29.0

Most Common Five-Year SDWIS Compliance Band

F

Counties with Data

63

of 63 total

County water atlas

Louisiana water signals by county

A state-level 2.5D view across drinking-water compliance, watershed impairment, monitoring density, and streamflow snapshot context. Pin any county, switch layers, then use the lens controls to compare index ranges, recorded violation rates, or impaired watersheds without leaving the page.

Counties

63

Avg SDWIS index

29.0

Watersheds

63

ATTAINS counties

Monitoring

62

22 fresh USGS snapshots

State atlas layers combine EPA SDWIS health-based violations, EPA ATTAINS 303(d) impairment assessments, EPA Water Quality Portal monitoring sites, and representative USGS NWIS streamflow gauges. Streamflow values appear only for fresh pipeline snapshots, not as a continuously updated stream. County pages include the observation time and year.

Prepared by ByCounty Editorial TeamPublished by WaterByCounty

Multi-source coverage in Louisiana

Beyond Drinking Water

EPA SDWIS

63/ 63

counties with drinking-water compliance data

2,895 health violations statewide (5yr)

EPA ATTAINS

89.9%

avg impaired across 63 counties

3,674 of 4,116 assessed bodies impaired

EPA WQP

1,400

monitoring sites across 62 counties

386,134 total readings (5yr window)

USGS NWIS

22

counties with a fresh pipeline snapshot

2 above20 below

State atlas notes

What stands out in Louisiana

County water quality is not one number. The strongest read comes from comparing drinking-water compliance against watershed impairment, monitoring density, and streamflow context. Use these signals as a starting point, then open any county profile for source-level detail.

Compliance spread

Assumption Parish has the highest value in the published state SDWIS Compliance Index table at 86.2/100, while Winn Parish has the lowest at 1.2/100. That is a 85.0 point gap inside one state.

Zero health violations

6

3+ health violations

53

Watershed pressure

The atlas impairment layer points to counties where assessed water bodies are most likely to miss state quality standards. Assessment density varies, so compare the percentage with the number of assessed bodies on the county page.

East Feliciana Parish100.0%Madison Parish100.0%Allen Parish97.2%

Monitoring hubs

East Baton Rouge Parish143 sitesSt. Tammany Parish83 sitesJefferson Parish67 sites

Lowest flow reads

Richland Parish0%Sabine Parish1%Vernon Parish2%

Highest fresh streamflow pipeline snapshots: Lafourche Parish (224%, observation 2026), Ascension Parish (168%, observation 2026), St. Mary Parish (73%, observation 2026). These are source-data observations, not household tap-water conclusions.

All Louisiana Counties

CountySDWIS Compliance Index
Assumption Parish86.2
Lafourche Parish86.2
St. Bernard Parish86.2
St. Charles Parish86.2
St. John the Baptist Parish86.2
Terrebonne Parish86.2
East Baton Rouge Parish71.9
Jefferson Parish71.2
Orleans Parish67.4
West Baton Rouge Parish62.3
West Feliciana Parish58.6
Jefferson Davis Parish52.6
Beauregard Parish48.9
East Feliciana Parish44.2
Livingston Parish42.0
Rapides Parish39.9
Vernon Parish38.6
Lafayette Parish37.5
Calcasieu Parish37.1
Pointe Coupee Parish36.4
St. Tammany Parish33.9
Tangipahoa Parish33.6
Vermilion Parish32.7
Iberia Parish30.7
Ouachita Parish29.1
St. James Parish28.5
Avoyelles Parish28.4
Caddo Parish28.1
Allen Parish22.3
St. Landry Parish22.2
Iberville Parish19.9
Webster Parish19.0
Acadia Parish16.9
Evangeline Parish16.7
St. Helena Parish16.7
Plaquemines Parish16.5
St. Martin Parish16.4
Ascension Parish16.3
Washington Parish15.5
Bossier Parish15.3
St. Mary Parish15.2
Catahoula Parish14.8
Lincoln Parish13.8
Claiborne Parish12.5
Franklin Parish11.5
West Carroll Parish8.7
Richland Parish7.7
Natchitoches Parish7.1
Madison Parish6.9
Morehouse Parish6.0
De Soto Parish5.9
Grant Parish4.8
Concordia Parish4.3
Cameron Parish4.0
East Carroll Parish3.8
Caldwell Parish2.9
Sabine Parish2.8
Red River Parish2.7
Bienville Parish2.5
Jackson Parish2.3
Tensas Parish2.0
Union Parish1.4
Winn Parish1.2

Frequently Asked Questions

Which Louisiana county has the highest SDWIS Compliance Index?
Assumption Parish has the highest SDWIS Compliance Index in the published Louisiana cohort at 86.2/100. This WaterByCounty relative comparison is not an EPA score and does not establish current conditions for a utility or address.
What does the Five-Year SDWIS Compliance Band mean?
The band is derived only from each county aggregation's recorded health-violation rate per 100,000 people served for the stated five-year source window. It is separate from the relative SDWIS Compliance Index and is not a current determination for a specific utility or address.
What does EPA ATTAINS report across Louisiana?
Across 63 published Louisiana county records with EPA ATTAINS data, 3,674 of 4,116 assessed water bodies are listed as impaired. This is a watershed assessment and does not describe finished household tap water.
Which USGS streamflow records are shown across Louisiana?
WaterByCounty has 22 fresh USGS pipeline snapshots in the published Louisiana cohort. Each county page shows its observation timestamp and year. A pipeline snapshot is not a continuously updated reading or a tap-water safety measure.
Where can Louisiana residents find current official information?
Review the applicable utility's Consumer Confidence Report, active notices, and the state drinking-water agency. WaterByCounty's county-level historical aggregations do not establish the current status of a specific utility, address, private well, or household plumbing system.
What does Water Quality Portal monitoring volume show in Louisiana?
The published county records contain 386,134 results from 1,400 monitoring locations in the site's five-year aggregation. Monitoring volume does not by itself indicate better or worse water quality.

Data Sources

Drinking-water compliance data from the EPA Safe Drinking Water Information System (SDWIS) via the ECHO enforcement database. The WaterByCounty SDWIS Compliance Index reflects the recorded rate and is not an EPA score.

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.

← Back to All States

Explore more data for Louisiana

Property TaxCost of LivingCrime RateIncomeHealthSchoolsDisaster RiskWeatherCounty Score