
Author
Logan Johnson
Founder & Data Editor
Builder and data editor of the ByCounty Network. I publish county-level data sourced exclusively from federal agencies — and I am personally accountable for every methodology decision on this site.
Logan Johnson is the founder and data editor of the ByCounty Network — a family of independent data-journalism sites that publish county-level statistics from primary U.S. government sources: U.S. Census ACS, FBI UCR, CDC, FEMA NRI, NCES, EPA, NOAA, USDA, and USASpending.gov.
His role is the data-editor role, not the subject-matter-expert role. He designs the data pipelines that pull each dataset, sets the methodology behind every composite score and ranking, spot-checks AI-generated narratives against the underlying statistics before publication, and signs off on every methodology change. He is not a CPA, physician, criminologist, real-estate broker, or other domain-credentialed professional. The site is a transparent data utility, not a professional advisory service.
When a feature genuinely requires domain expertise — a public-health analyst weighing in on CDC measure choice, a CPA reviewing a property-tax explainer — Logan recruits a named co-byline reviewer rather than fabricating credentials. The reviewer commitment for each site is documented on that site's editorial-standards page, including the recruit status when no domain reviewer is currently in place.
Outside the network, Logan has spent the last several years building data infrastructure for logistics and operations teams — work that translates directly into the pipeline discipline applied here: every statistic on the site is traceable to a primary source, every methodology decision is documented, and every page lists a "Last reviewed" date.
Coverage areas
- EPA SDWIS drinking-water compliance
- EPA ATTAINS Clean Water Act §303(d) watershed assessment
- EPA Water Quality Portal monitoring records
- USGS NWIS live streamflow data
Articles by Logan on Water By County
Understanding Drinking Water Quality by County
A data-driven analysis of drinking water quality across all US counties. How EPA SDWIS data reveals geographic patterns, grade distributions, and what drives water quality differences.
EPA Water Violations: What They Mean for Your Tap Water
What EPA drinking water violations actually mean, the different types of violations, which counties have the most, and what you can do if your county has a low water quality score.
Best and Worst Counties for Water Quality in America
The 25 best and 25 worst counties for drinking water quality in the United States, ranked by EPA compliance data. Geographic patterns, common factors, and what it means for residents.
Counties with the Best Water Quality
The 25 US counties with the best drinking water quality scores, ranked by EPA SDWIS compliance data. See which counties have the cleanest, safest tap water.
Counties with the Worst Water Quality
The 25 US counties with the worst drinking water quality scores, ranked by EPA SDWIS compliance data. See which counties face the most serious water quality challenges.
Counties with the Most Water Violations
The 25 US counties with the most EPA health-based drinking water violations. See where tap water systems have struggled with compliance and contamination.
Water Quality by State
State-by-state drinking water quality rankings based on average county EPA SDWIS scores. See which states have the best and worst tap water quality overall.
Counties with Zero Health Violations
All US counties with zero recorded EPA health-based drinking water violations. See which counties have perfect compliance records and the safest tap water.
Counties with the Cleanest Drinking Water
The US counties with both zero EPA health violations and A-grade water quality scores. The strictest standard for clean, safe drinking water in America.
Most At-Risk Water Supplies by County
The 25 US counties with the most at-risk water supplies — low EPA scores combined with active health violations. See where drinking water faces the greatest challenges.
Rural vs Urban Water Quality by County
How drinking water quality differs between rural and urban counties in America. Comparing EPA compliance data, violation rates, and scores by county characteristics.
Water Quality Grade Distribution Across US Counties
How many US counties earn A, B, C, D, or F grades for drinking water quality? A complete breakdown of the national grade distribution using EPA SDWIS data.