The river Druksa (Smalva) flows in Belarus and Lithuania, Dysna left tributary. Length of the river 84 km (38 km in Lithuania), catchment area 984 km ² (606 km ²  in Lithuania). Source 8 km to NE from Dukstas town. Flowing to the NE through the lakes Trilypis, Smalvykstis, Smalvos, Druksiai. From the source to the lake Druksiai called Smalva. Passing the lake Druksiai 4 km the river flows along the Lithuania - Belarus border, continue to Belarus. Flows into the river Dysna 118 km from its mouth at Kazenai village. The riverbed deep, banks are high. Average gradient of 24 cm / km. The river water regime is regulated by lakes. Average rated discharge below the lake Smalvos  0.32 m³ / s, below the lake Druksiai 4.48 m³ / s.

At high water level. Spring flood, or after heavy rains.
Strainers, shallows, beaver dams.
WW 0 (1-).

16.3  The west shore of the lake Smalvykstis. From Smalvos village 1.2 km.
15.2 The river Smalva flowing out from the lake Smalvykstis east corner. The river width  2-4 m. Strainers. The banks marshy.
14.9 left hillfort Vitkunai.
14.4 The Smalva  flows into the lake Smalvos.
11.2 The Smalva  flowing out from the lake Smalvos at north corner of the lake. Downstream the bridge, under the bridge the river flowing through two concrete pipes. The creek slowly flows through forests, the banks are low and marshy. In places splits into branches, sometimes shallow. The riverbed width 2-5 m. Many strainers, beaver dams, the creek in places quite fiddly navigated. The gradient to the small lake 47 cm / km.
7.9 Railway bridge. Under it small rapid. Pakalniskiai.
7.0 High-voltage line.
6.7 right small lake. A bit downstream right Karmelitai.
4.8 The Smalva  flows into the small lake overgrown by water plants.
4.5 The end of the small lake. The gradient to the lake Druksiai 24 cm / km.
3.1 Bridge. Under it the river flows  through three concrete pipes.
1.8 left S-1 flows from a lake.
1.7 right S-2 flows from the small lake.
0.0 The Smalva flows into the lake Druksiai. To Visaginas town approx. 3 km.