The Klejnárka originates in the territory of Dobrovítov in the Upper Sázava Hills at an elevation of 517 m (1,696 ft) and flows to Konárovice, where it enters the Elbe River at an elevation of 193 m (633 ft). It is 40.3 km (25.0 mi) long. Its drainage basin has an area of 350.0 km2 (135.1 sq mi).[1]
There are 395 bodies of water in the basin area. The largest of them is the Vrchlice Reservoir with an area of 87.6 ha (216 acres), built on the Vrchlice.[1] A system of ponds is built on the upper course of the Klejnárka. The largest of them is Zbýšovský Pond with an area of 10.6 ha (26 acres).[3]
Protection of nature
On the upper course of the river near the source, the Jánský potok Nature Monument was declared. It has an area of 4.2 ha (10 acres). The reason for protection is a set of water and meadow ecosystems with the occurrence of common minnow and other protected species of plants and animals.[4]