Aabach (Greifensee)

The Aabach (also "Aa", or "Ustermer Aa" for disambiguation with the Mönchaltorfer Aa) is a minor river in the canton of Zürich, Switzerland. At a length of , it flows from Pfäffikersee to the Greifensee. Its valley is known as 
"Aatal" ("Aa Valley"), eponymous of the settlement Aathal.