While the 100 largest cities in the world occupy less than 1 percent of our planet’s land area, their source watersheds cover more than 12 percent — 17 million km2 — that collects, filters and transports water to nearly a billion people before it ever enters a pipe It’s a startling reminder that not only does land far beyond city limits impact city water but that cities indeed shape the landscape around them by defining a route of development for both themselves and their neighbors.
The Urban Water Blueprint– a new report by The Nature Conservancy in partnership with C40 Cities Climate Leadership Group and the International Water Association — collected and analyzed three years’ worth of data in more than 2,000 watersheds and 530 cities worldwide. The report reveals the annual costs — and potential cost savings — of watershed conservation at scale.
The Return on Investment for Water Utilities
Sourcing information on reported water treatment plant operations and maintenance (O&M) costs from a sample of cities, the Urban Water Blueprint shows that reductions in sediment and nutrients by 10 percent leads on average to a roughly five percent reduction in treatment costs. If all possible conservation strategies were applied, global water savings on treatment plant O&M would be US $890 million per year.
Out of all 534 cities analyzed, one in four would realize a positive return on investment after implementing watershed conservation measures. The report estimates that 59 cities in the U.S. alone fall into this category, including Los Angeles, Portland, Ore., and Atlanta. Of course, the return on investment would vary widely among cities.
A well-known case study in New York City offers testimony to this return. In the 1990s the city needed to demonstrate to state and federal regulators that it could comply with the federal Safe Drinking Water Act. Officials discovered that building an additional water treatment plant would cost approximately $8-10 billion dollars, not including hundreds of millions in annual O&M. In contrast, they found they could meet the federal standards by protecting the city’s water source instead. Now, New York City is investing $1.5 billion over 10 years to preserve its forested watershed, acquire new land and restore critical habitats — ultimately keeping the water supply among the cleanest in the world.
Cities that embrace this strategy will recognize multiple benefits. In addition to improving water quality, source watershed conservation improves aquatic and terrestrial biodiversity. The strategies can also generate jobs in rural communities and recreational benefits for all to enjoy. These benefits are not as easily monetized but they offer untapped political capital to mayors and utility managers willing to do things differently.