Comparison of potential drinking water source contamination across one hundred U.S. cities

Sean W D Turner,Chris R Vernon,Ryan Mcmanamay,Jennie S Rice,Landon Marston,Kristian D Nelson,Kerim Dickson

doi:10.1038/s41467-021-27509-9

Abstract

Drinking water supplies of cities are exposed to potential contamination arising from land use and other anthropogenic activities in local and distal source watersheds. Because water quality sampling surveys are often piecemeal, regionally inconsistent, and incomplete with respect to unregulated contaminants, the United States lacks a detailed comparison of potential source water contamination across all of its large cities. Here we combine national-scale geospatial datasets with hydrologic simulations to compute two metrics representing potential contamination of water supplies from point and nonpoint sources for over a hundred U.S. cities. We reveal enormous diversity in anthropogenic activities across watersheds with corresponding disparities in the potential contamination of drinking water supplies to cities. Approximately 5% of large cities rely on water that is composed primarily of runoff from non-pristine lands (e.g., agriculture, residential, industrial), while four-fifths of all large cities that withdraw surface water are exposed to treated wastewater in their supplies.

Highlights

Drinking water supplies of cities are exposed to potential contamination arising from land use and other anthropogenic activities in local and distal source watersheds
As the demand for clean, piped water grew rapidly in the United States during the late 19th and early 20th centuries, dozens of major cities constructed centralized systems of surface water supply that often featured inter-basin transfers and reservoirs to import and store water from remote river basins[1]. These storage and conveyance systems were built during an era when the contributing source watersheds were mostly free from activities that could contaminate surface water
Our results explore the potential water quality implications of this diversity for the 116 largest cities in the U.S for four dimensions: comparing Point and Nonpoint PPCS across all large cities, determining hotspots of land use and anthropogenic activities across source watersheds serving large cities, examining the impact of source watershed diversity and hydrology on the PPCS results, and analyzing how the adoption of indirect potable reuse could affect

Summary

Introduction

Drinking water supplies of cities are exposed to potential contamination arising from land use and other anthropogenic activities in local and distal source watersheds. To quantify potential point and nonpoint anthropogenic contamination for these cities, we first combine spatially referenced regions of drinking water supply catchments with geospatial layers detailing the presence of human activities—namely croplands, economic sectors, industrial facilities, human settlements, and wastewater treatment plants.

Results

Conclusion