The Ahja (Estonian: Ahja jõgi) is a river in Estonia. The river is 103.4 kilometres (64.2 mi) long. The river begins at Lake Erastvere and empties into the Emajõgi River. The river's middle course is protected by the Ahja River Valley Landscape Conservation Area.

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  The Ahja in Lääniste in 2008
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  The Ahja near Valgemetsa
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  Kiidjärve watermill, built in 1914
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  Taevaskoja
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  Winter in 2016