Sutla

Sotla / Sutla
Sutla River in Zelenjak, between Klanjec and Kumrovec
Country	Slovenia, Croatia
Basin features
Main source	580 m (1,900 ft)
River mouth	Sava 135 m (443 ft) 45°51′52″N 15°41′01″E / 45.8645°N 15.6835°E / 45.8645; 15.6835Coordinates: 45°51′52″N 15°41′01″E / 45.8645°N 15.6835°E / 45.8645; 15.6835
Basin size	584 km2 (225 sq mi)
Physical characteristics
Length	89 km (55 mi)

The Sutla (Croatian) or Sotla (Slovene) is a river flowing through Slovenia and Croatia, mostly forming their border. It is a tributary to the Sava, itself a tributary to the Danube. It is 89 kilometres (55 mi) long and has a watershed area of 584 square kilometres (225 sq mi).

The Sutla flows through the following municipalities:

The hydrological parameters of the Sutla are regularly monitored in Croatia at Zelenjak.

The division of the Sutla/Sotla basin area between Croatia and Slovenia is inconsistent in sources - Croatian sources claim either 343 km² (132 sq mi) or 455 km² (176 sq mi), while Slovenian sources claim either 477 km² (184 sq mi) or 451 km² (174 sq mi)

The Kozje Park (Slovene: Kozjanski park), established in 1981 as the Trebče Memorial Park (Spominski park Trebče), is located in the Slovenian territory to the west of the Sotla. It covers 206 km² (80 sq mi) of the landscape of Kozje Hills (Kozjansko hribovje), including wetlands along the Sotla. It is the habitat of over 120 bird species and of about 950 higher plant species.

It's been suggested that the names "Sutla" and "Sava" are related, but this is uncertain. Another theory is that the name "Sutla" comes from the Indo-Europan root *su, meaning "swine".