40 RICHTER ET AL. | FEBRUARY 2018 • 110:2 | JOURNAL AWWA P ublic water providers face many challenges in meeting the needs and expectations of the communities they serve. Providing an adequate supply of safe water remains a preeminent goal of all urban water providers, of course, but the nature of the challenges inherent in continuously meeting that goal have changed dra- matically since the first public water supply systems were developed thousands of years ago. As public concerns over water continue to evolve in the 21st century, so too do perspectives on what “sustainability” might mean for urban water supply systems. Some of the earliest water supply systems date back to the period when human societies began shifting from hunting and gathering food and water to living in sedentary, agrarian communities. With this transition came a fun- damental shift in our vulnerability to the vagaries of weather and water avail- ability: instead of traversing the landscape to find water, we became largely dependent on water coming to us. Not surprisingly, the earliest population centers and ancient water supply systems developed where abundant and reliable water supplies could be extracted from adjacent rivers, lakes, and springs. Long before the concept of sustainability was formulated, communi- ties understood that they could only be sustained as long as their water uses remained within the limits of local water supplies. THE PERPETUAL NEED FOR SAFE WATER PRESENTS COMMUNITIES AND UTILITIES WITH 21ST-CENTURY CHALLENGES; A RECENTLY DEVELOPED SERIES OF INDICATORS CAN HELP IN ESTABLISHING AND MONITORING WATER SUSTAINABILITY EFFORTS. Feature Article BRIAN D. RICHTER, MARY ELIZABETH BLOUNT, CARA BOTTORFF, HOLLY E. BROOKS, AMANDA DEMMERLE, BRITTANY L. GARDNER, HALEY HERRMANN, MARNIE KREMER, THOMAS J. KUEHN, EMMA KULOW, LENA LEWIS, HALEY K. LLOYD, CHANTAL MADRAY, CHRISTINA I. MAUNEY, BENJAMIN MOBLEY, SYDNEY STENSETH, AND ALAN WALKER STRICK Assessing the Sustainability of Urban Water Supply Systems Layout imagery by Brian S/Shutterstock.com