Lake Šmartinsko is situated in the hilly hinterland of the Savinja Valley, approximately four to five kilometres north of the centre of Celje, nestled among the settlements of Šmartno v Rožni dolini, Brezova, Loče, and Prekorje. Covering an area of around 1.13 square kilometres (113 hectares) with a water volume between 4.5 and 5.5 million cubic metres, it is one of the largest artificial reservoir lakes in Slovenia. Due to the distinctly undulating original geomorphology of the flooded Koprivnica stream valley, the lake features an extraordinarily indented shoreline spanning over 12 kilometres. It is characterized by deep side bays, steep wooded peninsulas, a small island, and water depths reaching up to 15 metres near the main dam at its southern end.
The history of the lake's creation is closely linked to flood defence for the Celje Basin. Following catastrophic floods in 1954 and several subsequent high-water events—where the Savinja, Voglajna, and their torrential tributaries submerged the town centre and caused massive material damage—comprehensive hydro-amelioration projects were initiated. The construction of a high earthen dam in the gorge of the Koprivnica stream was completed in 1970, establishing a multi-purpose water reservoir. Its primary and strategic purpose was the retention of flood waves and discharge regulation, while secondary roles included providing process and irrigation water for Celje's industries and surrounding agriculture.
Over the decades, the lake gradually outgrew its strictly hydro-technical function. The shallower bays and reedbeds in the northern and western sections evolved into a valuable natural ecosystem and wetland habitat, sheltering rare marsh birds, aquatic amphibians, and rich flora. The area soon became one of the most renowned angling destinations in Slovenia; the Celje Angling Club manages an abundant fish stock here, with the lake being nationally famous for catches of trophy-sized carp, catfish, zander, pike, grass carp, and tench.
In the new millennium, Lake Šmartinsko underwent a thorough and deliberate revitalisation that completed its transformation into the central regional recreation park. The City Municipality of Celje developed an extensive network of themed walking and hiking paths. Among its most distinctive attractions are a picturesque wooden floating pontoon bridge that spans across one of the bays to connect the circular walking loop, and a modern boating pier.
Today, the lake offers a wide range of experiences for all generations: from rowing, kayaking, tourist boat rides, and stand-up paddleboarding to birdwatching, running, and cycling. The shoreline infrastructure includes themed children's playgrounds, educational didactic panels about the forest and aquatic life, and contemporary catering facilities. Lake Šmartinsko thus stands as an exceptional example of harmony between urban flood protection, natural biodiversity preservation, and modern tourist-recreational land use.
Tourist boat on Lake Šmartinsko in 1996