Fair — Average Score 69/100
State Overview
Water quality across Idaho receives an overall grade of C (Fair) with an average score of 69 out of 100, based on EPA compliance data from 235 ZIP codes statewide. This is 6 points below the national average of 75, suggesting significant water quality challenges that affect residents statewide. Approximately 23% of ZIP codes (55 areas) receive a D or F grade, indicating communities with notable water quality concerns that warrant attention. The lowest-scoring area is ZIP code 83607 (Caldwell) with a score of 25/100. 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