The Ombla is a short river in Croatia, northeast of Dubrovnik. Its course is approximately long, and it empties into the Rijeka Dubrovačka embayment of the Adriatic Sea near Komolac in Dubrovnik-Neretva County. Rijeka Dubrovačka is actually a ria, a flooded river valley formed through changes in sea surface elevation on a geologic time scale. The river rises as a karst spring fed by groundwater replenished by Trebišnjica, which is an influent stream flowing in Popovo Polje, in the immediate hinterland of the Ombla. The elevation difference between the river's source and its mouth is just over . The average discharge of the river is per second. The drainage basin of the Ombla encompasses and, besides the short surface course, includes only groundwater flow.
The Ombla is used as a source of drinking water for Dubrovnik's water supply network, and construction of a hydroelectric power plant has been planned for the past two decades. , the plans entail construction of a subsurface reservoir and a 68 megawatt power plant. The plan sparked controversy amid doubts raised with respect to environmental protection and biodiversity management, technical and financial feasibility, and procedural problems related to the project. A particular concern expressed was that the underground reservoir might trigger earthquakes.