Study Published on Drinking Water Treatment Costs Associated with Watershed Degradation

The findings of a study about the impact of watershed degradation on drinking water treatment costs has been published in the Proceedings of the National Academy of Sciences (PNAS).  The study is entitled, “Estimating Watershed Degradation Over the Last Century and its Impact On Water-Treatment Costs for the World’s Large Cities.”  The study uses raw water quality data from the drinking water intakes of 309 large cities across the globe, combined with long-term data on anthropogenic land-use change in their source watersheds, and data on water-treatment costs to determine the type and intensity of water treatment needed to reach drinking water standards.  Anthropogenic activity is highly correlated with sediment and nutrient pollution levels, which is in turn highly correlated with treatment costs.  The findings show that:

  • Globally, urban source watershed degradation is widespread, with 9 in 10 cities losing significant amounts of natural land cover in their source watersheds to agriculture and development.
  • Watershed degradation has impacted the cost of water treatment for about one in three large cities globally, increasing those costs by about half.
  • This increase in cost matters because increases in water-treatment costs are paid for by those living in cities, so watershed degradation has had a real quantitative cost to hundreds of millions of urbanites.

To read the full article, visit the PNAS website.