Pond filling with large windmill-Clinton, Illinois by Paul Behrends | Feb 17, 2014 | Windmill Service This 12′ D702 Aermotor windmill atop 47′ tower pumps constantly to keep a 2 acre pond full. We are using a 2″ open top cylinder set about 200′ down. Mill is on a pretty good hill above all wind obstructions. Does nice job of keeping pond full.