Údolní nádrž Vír I, lake in the Czech Republic

Údolní nádrž Vír I is a reservoir on the Svratka River above the village of Vír, held back by a concrete dam whose crest carries a railing and walkway, with vertical buttresses on the grey downstream face and a white flat-roofed building at its foot. The lake reaches 223.5 ha. Its water is drinking water, so the shores are closed to recreation and fishing.

The dam was built in the mid-20th century to secure a reliable water supply for the growing needs of the region. Its construction flooded the original valley of the Svratka, including parts of several small communities that once stood there.

The reservoir's name comes from the village of Vír below the dam. Its water is piped to Brno and the Bystřice, Nové Město na Moravě and Žďár areas through the Vír regional water main. Because of the first-zone hygiene protection order, recreation and fishing are banned, so the only waterside route is an asphalt cycling path to Dalečín.

Recreation and fishing are banned around the reservoir under the first-degree hygiene protection zone, so swimming and shoreline access are not possible. The one permitted route is an asphalt cycle path on the right bank leading to Dalečín, and a water-management educational trail is also open. The dam stands above the village of Vír on the Svratka.

The dam's construction erased the village of Chudobín u Dalečína and nearly all of Korouhvice; their sites now lie under the water. A water-management educational trail and an asphalt cycle path to Dalečína were later opened as small concessions in the protected zone.