The Sotla river basin
|The Rogaška Slatina Municipality (Slovenia) and the Hum na Sutli Municipality (Croatia) are neighbouring communities situated along the border between Republic of Slovenia and Republic of Croatia. They are separated by the Sotla River which is the borderline between Slovenia and Croatia. The Sotla catchment is part of the Sava river basin, which in turn is part of the Danube basin.
Since the Sotla is a border river, its management and flood prevention strategies are subject to both countries. Due to frequent floods in the past, there was already an initiative in the former Yugoslavia to prevent floods by building an artificial water storage lake. The plans were implemented and the lake was put into operation in 1980 by building two dams. It got the name Vonarje Lake. Because after each flood the remaining water quality was unacceptable, the lake was abolished in 1986, but the dams are still in place (however they need to be modernized).