Nagavali River rises in the eastern slopes of the Eastern Ghats near Lakhbahal in the Kalahandi district of Odisha at an elevation of about 1,300 metres. Another name of the river Nagavali is Langulya. The geographic co-ordinates of the river are north latitudes 18 10 to 19 44 and east longitudes of 82 53 to 84 05. Niyamgiri hills where Bauxite mining is proposed are located in Nagavali river basin.
The total length of the river is about 256 km, of which 161 km are in Odisha and the rest in Andhra Pradesh. The catchment area of the basin is 9,510 square km. Nagavali is an interstate river with 4462 km2 and 5048 km2 river basin area located in Odisha and Andhra Pradesh respectively. The river basin receives 1000 mm average rain fall annually. The uplands of the river basin are hilly areas with predominantly tribal populated. It drains parts of the Kalahandi, Rayagada and Koraput districts of Odisha and Srikakulam, Vizianagaram districts of Andhra Pradesh.
The main tributaries of the River Nagavali are Jhanjavati, Barha, Baldiya, Satnala, Sitagurha, Srikona, Gumudugedda, Vottigedda, Suvarnamukhi, Vonigedda, Relligedda and Vegavati. The Suvarnamukhi river takes its birth in the hills of Salur mandal and takes an eastern direction and finally join the Nagavali at Sangam village in Vangara mandal of Srikakulam District. Vegavathi originates in pachipenta hills of Pachipenta Mandal.
Vegavathi River takes its origin in the Pachipenta hills in Eastern Ghats. It is a tributary to Suvarnamukhi, which in turn is a tributary to River Nagavali. Salur town and Paradhi are located on the banks of this river. There are two road bridges at these places.
Jhanjavati Project18°51′49″N83°26′05″E / 18.86361°N 83.43472°E / 18.86361; 83.43472 is located at Rajyalaxmipuram village in Komarada mandal of Vizianagaram district on Jhanjavati, a tributary of River Nagavali. It is a rubber dam and first of its kind in Andhra Pradesh and India and the biggest in Asia. It is aimed to utilize 4 TMC of available water and to irrigate / stabilize a total ayacut of 24,640 acres in Vizianagaram District. It was dedicated to the nation on 1 January 2006 by Chief Minister Y.S.Rajasekhar Reddy. The rubber dam was installed on a concrete plate in technical collaboration with Hydro-Construct of Austria. Its size would be raised or reduced with the help of water pumped into it. It was planned to fix the rubber dam to a height of three metres to store water up to 125 metres (410 ft) msl in the reservoir without causing submergence in the Odisha side of the river. However, the prior agreement between Odisha and Andhra Pradesh on this project permits to raise the maximum reservoir level submerging Odisha area up to 480 ft msl. This dispute is unsettled till now preventing use of the project's full irrigation potential for last 20 years due to present 0.6 tmcft reservoir storage capacity against 4 tmcft planned storage. Andhra Pradesh wants to resolve the issue by constituting Nagavali water dispute tribunal under the Interstate River Water Disputes Act as the dispute is not getting settled by negotiations between the two states.
Thotapalli Reservoir is located at village Thotapalli in Vizianagaram district and presently being upgraded as barriage.
Madduvalasa Reservoir is located at Madduvalasa village in Vangara mandal of Srikakulam district. It is built across Vegavati and Suvarnamukhi tributaries. The project is started in 1977 and provides water for 15,000 acres of land for cultivation.