The river Asva flowing in Silalė and Silutė districts, the river Veivirzas left tributary. Length of the river 52 km, the catchment area 212 km ². Source 2 km west from Pajuralis village at Samogitian highlands southwest edge. Flowing to west across old valleys, only places with them the same is a short the Asva riverbed sections. Flows into the river Veivirzas 20 km from its mouth near Luisiai village. Average gradient 180 cm / km. Narrow valley, sometimes deep. Rated discharge at the mouth: max. 40 m³ / s, avg. 2.71 m³ / s. Runoff module is 12.8 liters / s of km ².

At higher water level. Spring, or after heavy rains.
Shallows, rapids, strainers.
WW 1 (1+).

23.2  Sveksna - Siliai road bridge. left Siaudenai. The gradient to Inkakliai village  158 cm / km. Riverbed width  6-10 m. Rare small rapids. The banks are steep in places, overgrown bushes, trees, may be several strainers.
21.7 right A-2. right Vilku Kampas.
21.0 left Ziogai.
20.4 left Zvelesys. left Stankiskiai.
19.2 right Sveksnale. right Vilku Kampas.
18.9  Sveksna - Gardamas road bridge. left Tvaskuciai.
16.8 Bridge. right Nikeliai.
15.5 right Vilnutis.
15.2 Small bridge. left Paulaiciai. Small rapid.
15.0 left Berzupis. left hillfort Paulaiciai.
14.2 Road ford. A little upstream small bridge. left Raudiske. right Inkakliai. To the mouth the river flows through forests. Rare strainers.
13.9 Small bridge.
10.9 Sveksna - Saugai road bridge. right Inkakliai. The gradient to the mouth 44 cm / km. The river current is calmer. Rare strainers.
10.5 Small bridge.
8.5 right Jurgaiciai.
7.7 right Telsina. right Jomantai. right hillfort Jomantai.
6.6 right Greizina.
4.4  Sveksna - Vilkyciai road bridge.
0.8 right Vatina. right hillfort Uoksai.
0.0 The Asva flows into the river Veivirzas.