Nádrž Tesák, Natural monument in Rajnochovice, Czech Republic.

Nádrž Tesák is a concrete water reservoir in the village of Rajnochovice that fills naturally with rainwater and maintains a relatively shallow depth. The basin provides suitable habitat conditions for several protected amphibian species found in the area.

The concrete basin was built beside the mountain hut Tesák, which burned down on the night of 28–29 January 2022; the hut's site now falls within the 50 m protective buffer around the monument. The reservoir is a natural monument cared for by the Zlín Region authority, protecting the Carpathian newt (Lissotriton montandoni), a Carpathian-Sudeten endemic listed as critically endangered under decree 395/92 Sb.

The reservoir is named after the Tesák mountain hut that stood about 20 metres to its west until it burned down on the night of 28–29 January 2022; the hut's site now falls within the 50-metre protective buffer. The pool is known among naturalists for the hybridisation of Carpathian newts with smooth newts recorded here.

The reservoir lies at 690 m in the Hostýnské vrchy, about 20 m east of the former Tesák mountain hut site and 850 m northeast of the Kyčera summit (757 m). It holds water only to a depth of roughly 40–90 cm, fed solely by rainfall. The 50 m protection zone around the natural monument also covers the hut's former footprint.

The reservoir is the only known site in the area where Carpathian newts (Lissotriton montandoni) hybridise with common newts (Lissotriton vulgaris). The Carpathian newt is a Carpathian-Sudeten endemic listed as critically endangered under Czech decree No. 395/1992. Night surveys also recorded the soprano pipistrelle and brown long-eared bat around the water.