Pipurger Speicher, Natural monument lake near Oetz, Austria

Pipurger Speicher is a mountain lake near Oetz in the Ötztal region, nestled between steep Alpine slopes. Fed by mountain streams, the water fills a natural basin surrounded by rocky terrain and sparse vegetation.

The basin was originally a valley furrow parallel to the Ötztal; after the last ice age a mountain slide blocked its south-eastern end, damming the lake and diverting the Ötztaler Ache. First mentioned in 1282, when Count Meinhard II gave it to Stams Abbey, it was sold in 1860 for 200 gulden to Johann Leitner, who failed to drain it. In 1929 owner Meinhard von Pfaundler obtained protection, and in 1980 Oetz bought three quarters of the lake.

The lake gives its name to the hamlet of Piburg above Oetz. Since 1980 the municipality of Oetz has owned about three quarters of it and runs the bathing and boat facility at the eastern end. A mobile lake stage has hosted the concert series "Musik am Piburger See", and the hobby triathlon "Piburger Seawurm" has been held here. Legends tell of a farmstead and a dragon sunk beneath the water.

A hiking trail circles the lake, and a public bathing area with rowboat rental sits at the eastern end. The western end has flatter banks, while the rest of the shore drops steeply. The lake lies about 100 metres above the Ötztal, reachable on foot from Oetz or via the Piburger Straße (L310) to Piburg.

Almost 40% of the lake's water arrives underground rather than through the Piburger Bach, its only surface inflow, which discharges 6 to 22 litres per second at the west bank. Since 1970 an Olszewski pipe has drawn oxygen-poor, nutrient-rich deep water out of the basin, helping the lake reach a stable mesotrophic state.