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San Mateo County — Trends
Water Quality Trends: San Mateo County, California
Overview
Testing
Data
Trends
Contaminant Overview
Analyte Analysis
Neighbors
San Mateo County, California
All Contaminants — Exceedance Rate Over Time
% of sampled wells exceeding EPA limit per year · hover for detail
All years
Last 10 years
Last 5 years
Exceedance rate:
0%
10%
30%
50%+
· click a cell for detail
No time-series data available for this county.
San Mateo County, California
Analyte Trend
Median concentration over time with EPA limit reference
All years
Last 10 years
Last 5 years
Median (ppb)
IQR (p25–p75)
EPA MCL
Sample count
No time-series data for the selected contaminant.
San Mateo County vs. Neighbors · California
Neighbor Comparison
% of wells exceeding EPA limit across neighboring counties
All years
Last 10 years
Last 5 years
No shared time-series data found for this contaminant across neighboring counties.