The Kamniška Bistrica River rises from karst springs at an elevation of 623 metres in the terminal part of the valley. The river, which has a torrential character, is 32.7 km long and flows into the Sava River as a left tributary at an elevation of 265 metres.

Water from the springs beneath landslide rocks, which collect water from below Kamniški dedec (1,576 m a.s.l.) and the torrential ravine of Repov kot, flows into a small pond dammed by a concrete sill. The great erosive power of torrents in this area is evidenced by numerous landslide blocks and boulders in the channel itself. One kilometre downstream lies the narrow gorge known as Veliki and Mali Predoselj. Above these channels, two landslide boulders are wedged in place like natural bridges.

The river receives several tributaries in its upper course, including Kamniška Bela, Dolski graben (with a 15-metre waterfall), and the Črna and Bistričica streams near Stahovica. Historically, industry along the Kamnik–Domžale axis was a major source of pollution. Even in the 1970s, the river in Kamnik was blood-red due to a slaughterhouse.

Pollution and Environmental Status

While industrial pollution has decreased since the decline of local factories, the river still faces challenges. Wastewater and slurry are sometimes discharged or seep into the channel, often legally through permits or "sabotage-like" illegal discharges at night. Despite the water appearing clear in summer, bathers should remain cautious of these seeping pollutants. At Študa, a central wastewater treatment plant serves the municipalities of Domžale and Kamnik.

Mill Channels and Confluence

A characteristic feature of the river are the numerous mill channels. Approximately 200 km of diversion canals were once constructed, with about 60 km still active today. Near Podgrad lies the confluence of three rivers: the Ljubljanica, the Sava, and the Kamniška Bistrica—a site where Romans once built the Sava Fluvia fortress.

Boštjan Burger, 3 January 2023