Lower record-based concern — Population-weighted indicator 95/100
State Overview
Water quality across Oklahoma receives an overall grade of A (Lower record-based concern) with an average score of 95 out of 100, based on EPA compliance data from 378 ZIP codes statewide. This places Oklahoma 20 points above the national average of 75, indicating relatively strong water quality management across the state. Approximately 7% of ZIP codes (27 areas) receive a D or F grade, indicating communities with notable water quality concerns that warrant attention. The lowest-scoring area is ZIP code 73521 (Altus) with a score of 45/100. Scores are calculated from EPA Safe Drinking Water Information System (SDWIS) violation records, lead and copper testing results, PFAS monitoring data from UCMR5, and enforcement actions over the past 5 years.
Lowest Scoring ZIP Codes