Top 10 US Metros by Combined Air and Water Quality
PlainCompare ranks metros by composite environmental quality combining EPA AQI and SDWIS water-violation metrics.
Research period:
Research question
Among US metros with environmental quality data, which carry the cleanest combined air and water profile, and how does environmental quality correlate with the broader composite life score?
Methodology
This ranking reflects the data currently in our database, sourced from the agency referenced in the citation below and updated automatically as new filings are processed.
Coverage and exclusions: the source agency occasionally suppresses values for confidentiality, small sample size, or quality control, and suppressed rows are excluded from this ranking rather than shown as zero. If the agency later revises a figure, the revised value replaces the old one automatically the next time our data is refreshed.
Data provenance: we pull each release as it becomes available and normalize it into our database; a later release simply supersedes the one before it, so readers never see a mix of old and new figures on the same page.
Comparability across years: when the source agency revises its release schedule, definitions, or coverage, we note the affected years on the methodology page so readers can compare like-with-like rather than across a changed measurement.
Editorial governance: a named editor reviews every ranking page before publication (see the byline above). If an entity disputes a figure attributed to it, corrections are checked against the official source record before any change is made.
Every number on this page can be traced back to its source by following the entity links and the citation below, so independent verification never requires anything beyond the original public source.
See the methodology page for the complete ETL pipeline, source vintage, and column lineage.
Top 10 US Metros by Combined Air and Water Quality
Live data: reflects the current dataset
The ranked top 10
Every row below reflects the current 10-record dataset. Reload the page after new data is processed to see the latest values.
| # | Metro | State | Median AQI | Good AQI days % | Water safety |
|---|---|---|---|---|---|
| 1 | Duluth, MN-WI | MN | 39 | 78.14 | 62.1 |
| 2 | St. Cloud, MN | MN | 39 | 77.05 | 62.1 |
| 3 | La Crosse-Onalaska, WI-MN | WI | 37 | 96.1 | 35.8 |
| 4 | Fond du Lac, WI | WI | 38 | 92.68 | 35.8 |
| 5 | Rochester, MN | MN | 44 | 63.93 | 62.1 |
| 6 | Kahului-Wailuku, HI | HI | 21 | 99.73 | 25.3 |
| 7 | Mankato, MN | MN | 45 | 61.64 | 62.1 |
| 8 | Urban Honolulu, HI | HI | 31 | 98.36 | 25.3 |
| 9 | Myrtle Beach-Conway-North Myrtle Beach, SC | SC | 40 | 78.85 | 44.5 |
| 10 | Wausau, WI | WI | 37 | 84.97 | 35.8 |
Source: U.S. Environmental Protection Agency and FEMA, EPA AQS air-quality monitoring plus SDWIS water-violation registry plus FEMA NRI hazard scoring. Values reflect the current dataset, refreshed as new filings are processed. U.S. Environmental Protection Agency and FEMA, EPA AQS air-quality monitoring plus SDWIS water-violation registry plus FEMA NRI hazard scoring. Values reflect the current dataset, refreshed as new filings are processed.
Findings
Top entity in the ranking
The top-ranked record in this dataset is Duluth, MN-WI, with a value of 78.14 on the Good AQI days % column. The full top-10 set is rendered in the table above. Every value comes directly from the current dataset; no number is hardcoded into this page. When the source agency publishes a revision, the ranking and the prose around it update automatically.
Distribution shape
The gap between the top-ranked record (78.14) and the 10th-ranked record (84.97) characterizes how concentrated the top of the distribution is. Where the top value is many multiples of the median value of the visible set, the population is highly concentrated, a small number of entities accumulate the bulk of the measured quantity. Where the top and bottom of the visible set are close together, the distribution is relatively flat across the top end. The full distribution beyond this top-10 cut is summarized in the aggregate context section below and explored in the linked entity profiles.
Aggregate context
Across the full population behind this ranking, here are the summary statistics: how many records exist in total, the sum of the ranking metric across all qualifying records, and the mean per-record value. The methodology page documents the exact filter applied (records with null or zero values on the ranking metric are excluded). This aggregate row is computed from the same dataset that powers the ranking above.
Source provenance
The records in this ranking originate from U.S. Environmental Protection Agency and FEMA, specifically the EPA AQS air-quality monitoring plus SDWIS water-violation registry plus FEMA NRI hazard scoring. PlainCompare ingests the source vintage published by the agency and keeps this page current, there is no static export carrying stale numbers, and a newly published dataset is reflected here within hours. The methodology page documents the source URL, the vintage date, and the steps applied to prepare the data.
Why this ranking matters
Rankings like this one let a reader scan a population quickly and identify outliers, concentrations, and patterns that warrant deeper investigation. The detail pages linked from each entity in the table above give the full per-entity context: time-series history where available, related metrics from adjacent tables, and links onward to the underlying source records. The methodology page explains how an entity earns inclusion in the dataset and how the ranking column is computed at the source.
What this analysis cannot tell us
EPA AQI data aggregates to metro-level from underlying monitor stations, and metros with sparse monitor coverage can produce AQI medians that under-represent localized pollution. The good-days-percent column uses the EPA's six-category AQI band (Good, Moderate, Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy, Hazardous); the threshold for Good is AQI ≤ 50. Water safety scores derive from SDWIS violations against community water systems serving the metro; rural-fringe systems serving a fraction of metro population can amplify reported violation counts without meaningfully affecting the dominant urban water system. The water_safety_score column normalizes raw violation counts against a fixed denominator; users should consult /methodology/ for the exact formula. FEMA NRI disaster scores reflect expected annual loss across 18 hazard categories using 1990s-2010s historical data and may understate emerging climate-driven risk profiles. Environmental metrics are vintage-snapshots and do not capture transient events like wildfire-smoke days or short-duration violations.
Secondary cut from the same source
Top 10 by FEMA NRI-derived disaster safety score (low expected annual loss)
Sources
- U.S. Environmental Protection Agency, Air Quality System (AQS) - https://www.epa.gov/aqs
- EPA Safe Drinking Water Information System (SDWIS) - https://www.epa.gov/enviro/sdwis-search
- FEMA National Risk Index for Natural Hazards - https://hazards.fema.gov/nri/