Fig. 4: Regional hotspots of land use pressure.
From: Comparison of potential drinking water source contamination across one hundred U.S. cities
Presence of land development by % watershed area upstream of city water supply intakes (a–c) and number of facilities registered with National Pollutant Discharge Elimination System of the U.S. Environmental Protection Agency in those watershed areas (e, f). In each panel, the cities highlighted in the map and bar chart correspond to cities of the quantile shaded in the distribution plots. This is the upper quintile (80th percentile and above) for all panels except (c), which highlights the lower quantile. **Lower quantile excludes groundwater-only cities (n = 12). Bar color is by U.S. Census division (illustrated in each map).
