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 11.2 km, it flows from Pfäffikersee to the Greifensee. Its valley is known as Aatal ("Aa Valley"), eponymous of the settlement Aathal.