The Raška originates from a strong well and several sinking streams flowing out from the cave south of the Sopoćani monastery, in the Pešter region. Waters of the well and the sinking streams flowing from the Koštan-Polje are gathered into the catchment which enabled construction of the small subterranean hydro electrical power plantRas. The Raška flows northward during the entirety of its flow and is received at the village of Pazarište the Sebečevačka reka from the right, between the villages of Dojeviće and Vatevo much longer Ljutska reka from the left and Jošanica from the right at the town of Novi Pazar, the most populous settlement on the river's course. As it enters the Raška oblast, eastern part of the much larger Stari Vlah-Raška Region of the southwest Serbia, the river flows next to the old Petrova church and Novi Pazar's suburbs of Banja and Postenje. The lower course is not densely populated, except for the villages of Požežina and Milatkoviće. Finally, the river reaches the town of Raška and its suburb of Supnje, where it empties into the Ibar river.
The river, its tributaries and other rivers in its watershed are known for flash-flooding. Town of Novi Pazar was often being hit by sometimes catastrophic floods which caused a lot of damage. In 2010, the hydrology institute "Jaroslav Černi" from Belgrade drafted a project for mini, anti-erosion dams on the river and its tributaries, and other anti-flooding measures. The project was green-lighted and the municipalities of Novi Pazar, Raška and Tutin jointly began the construction. By 2013, 7 dams were built, which already proved useful during the 2014 floods. By 2018 additional 6 dams were built, lifting the total number to 13. In July 2018 additional 4 were under construction.
A floating dam which holds the plastic waste from the river was placed on the Raška river in April 2017. It is a pilot project and first such a facility in Serbia. The dam is placed on the location in the Raška municipality, but the closest settlement is the small village of Batnjik, which belongs to Novi Pazar. It soon got detached but was fixed again. After heavy rains in February 2018, in only 2 days, over 3 tons of plastic waste was held by the dam. The plastic is being baled and sent to recycling. The authorities in Novi Pazar which, as a large settlement, pollutes the Raška river the most, expressed interest in placing several other floating dams on the river on their territory, while the state government announced that if the project is successful, such dams will be placed all over Serbia.
