On October 20-21 of 1996, 8.9 inches of rain fell in Cambridge including on the 7.2 mile Alewife watershed, which drains runoff from three towns: Arlington, Belmont and Cambridge. Over the course of a day-and-a-half, the Alewife Brook spills over its banks and creeps across Rt. 16, eventually shutting it down. Homes that have been dry for 50 years flood. Some have water five feet and higher in their basements. Catch basins fountain. Traffic engineer Steve Kaiser measures the high point on the Arthur D. Little’s (now Discovery Park) Building 15 at 5.5 feet above normal, 7.0 feet above sea level.