US Water Intelligence Insights
National analysis across all 3,144 US counties — drinking water compliance, watershed health, monitoring records, and streamflow snapshots. Sourced from EPA SDWIS, ATTAINS, WQP, and USGS NWIS.
SDWIS
3,067
compliance records
ATTAINS
1,922
watershed assessments
WQP
2,975
counties monitored
NWIS
2,297
live streamgages
Key Findings
Drinking water compliance varies significantly across the United States. Hawaii leads with an average SDWIS water score of 78.6, while Oklahoma sits lowest at 15.8. The national average is 50.0 across 3,067 counties with reporting.
Watershed impairment averages 31.4% nationally across the 1,922 counties with EPA ATTAINS assessments — 76,513 of 1,858,139 assessed water bodies fail Clean Water Act §303(d) quality standards.
Monitoring density isn't uniform: 2,975 counties have water-quality records in the federal Water Quality Portal, with 134,550 monitoring sites contributing 42,870,911 measurements in the past five years.
Live streamgages report from 2,256 counties. Right now, 361 are running above typical, 1,762 are running below, and 133 are near their long-term mean — useful for flood watch, drought signal, and source-water context.
State Water Score Rankings
Average water quality score by state. Higher scores indicate better water quality.
Best Water Quality States
Lowest Water Quality States
Water Grade Distribution
How counties are distributed across water quality grades (A–F).
Violation Count vs. Water Score
Each point is a US county. Counties with more violations tend to have lower water scores.
Violations per 100K Served by State
Average population-normalized health violation rate by state.
Highest Violation Rates
Lowest Violation Rates
Top 10 Counties by Water Score
The counties with the best water quality scores nationwide.
EPA ATTAINS · Clean Water Act §303(d)
Watershed Impairment Distribution
Counties bucketed by the share of assessed water bodies that fail Clean Water Act quality standards. Only counties with reported §303(d) assessments are included.
0–10% impaired
609
31.7% of assessed counties
10–30%
374
19.5% of assessed counties
30–60%
622
32.4% of assessed counties
60%+
317
16.5% of assessed counties
Most impaired counties
| County | Impaired |
|---|---|
| Prince of Wales-Hyder Census Area, AK | 100.0% |
| East Feliciana Parish, LA | 100.0% |
| Dawes County, NE | 100.0% |
| Evangeline Parish, LA | 96.8% |
| Morehouse Parish, LA | 96.7% |
| Franklin Parish, LA | 96.6% |
| East Carroll Parish, LA | 95.2% |
| Union Parish, LA | 94.7% |
| Allen Parish, LA | 94.6% |
| Jefferson Davis Parish, LA | 94.1% |
Cleanest assessed counties
EPA Water Quality Portal · 5-year window
Most-Monitored Counties
Counties with the densest water-quality monitoring footprints. More sites and more readings generally mean stronger scientific evidence behind any reported signal.
| County | Monitoring Sites |
|---|---|
| Lee County, FL | 3,187 |
| Pinellas County, FL | 2,464 |
| Hillsborough County, FL | 2,243 |
| Maricopa County, AZ | 2,090 |
| Charlotte County, FL | 1,704 |
| Barnstable County, MA | 1,135 |
| Orange County, FL | 933 |
| St. Louis County, MN | 927 |
| Rosebud County, MT | 902 |
| Sarasota County, FL | 875 |
Counts include federal, state, and tribal monitoring locations. Each reading is a single sample analyzed for one characteristic.
USGS NWIS · Live streamgages
Rivers Far From Their Long-Term Mean
Counties whose primary streamgage is currently flowing well above or well below typical. Above-typical can signal storm runoff; below-typical can signal drought stress on source water.
Top 10 above typical
| County | vs typical |
|---|---|
| Tishomingo County, MS LITTLE YELLOW CREEK EAST NR BURNSVILLE, MS | 3690% |
| Duval County, FL ST. JOHNS RIVER AT JACKSONVILLE, FL | 2892% |
| Yalobusha County, MS OTOUCALOFA CREEK CANAL NR WATER VALLEY, MS | 2047% |
| Scurry County, TX Colorado Rv at Hwy 350 nr Ira, TX | 1905% |
| Kemper County, MS SUCARNOOCHEE RIVER NR PORTERVILLE, MS | 1587% |
| Sterling County, TX N Concho Rv at Sterling City, TX | 1391% |
| Honolulu County, HI Waikele Str at Waipahu, Oahu, HI | 1337% |
| Otero County, CO ARKANSAS RIVER AT LA JUNTA, CO | 1327% |
| Hendry County, FL THREE MILE CANAL BELOW G409 NEAR CLEWISTON, FL | 957% |
| North Slope Borough, AK COLVILLE R AT UMIAT AK | 955% |
Top 10 below typical
| County | vs typical |
|---|---|
| Lauderdale County, AL TENNESSEE RIVER AT FLORENCE AL | 0% |
| Cochise County, AZ SAN PEDRO RIVER NEAR TOMBSTONE, AZ | 0% |
| Maricopa County, AZ GILA RIVER BELOW PAINTED ROCK DAM, AZ | 0% |
| Pinal County, AZ GILA RIVER NEAR MARICOPA, AZ. | 0% |
| Santa Cruz County, AZ SANTA CRUZ RIVER AT TUBAC, AZ. | 0% |
| Craighead County, AR Cache River at Egypt, AR | 0% |
| Kern County, CA KERN R A ENOS PARK FOOT BR NR BAKERSFIELD CA | 0% |
| Orange County, CA SANTA ANA R A SANTA ANA CA | 0% |
| San Benito County, CA SAN BENITO R BL HOSPITAL RD BRIDGE NR HOLLISTER CA | 0% |
| San Diego County, CA SANTA MARGARITA R A YSIDORA CA | 0% |
Snapshot from the latest USGS reading per county at build time. Refreshes when the data pipeline runs.