In 1913, the Olivebridge Dam was sealed. It created the reservoir which provides New York City with up to 40 percent of its fresh water. The story begins in 1899, when surveyors chose the site along the Esopus Creek. But it was also home to more than 2,300 residents. Almquist describes the engineering feat of the century using modern techniques and local material, and how the building of the Ashokan Reservoir impacted its engineers, workers and residents.