The river Alsia flowing in Kaisiadorys and Prienai districts, the river Verkne right tributary. Length  38 km, the catchment area 135 km ². The river flows out of the lake Sventys, 9 km to the northwest  from Aukstadvaris town. Flows into the river Verkne 25 km from its mouth, a little below the Stakliskes town. Average gradient 275 cm / km. Valley brighter at lower course. Rated discharge at at the mouth: maximum 30 m³ / s average 1.06 m³ / s, minimum 0.1 m³ / s. Itis a lot lakes in  the Alsia catchment area, they regulates the river runoff, even in the summer it's pretty watercore and tidal amplitude of less than 1m. By the Alsia (Piestuvenu) lake called Alsycia.

Upper section to the lake Alsia at high water level. Spring flood, or flood after heavy rains. Section from the lake Alsia to the mouth all year, but not recommended in dry summer.
Shallows, rapids, boulders, strainers, dam.
WW 1. Upper section to the lake Alsia WW 2 (2+).

33.0  Medzioniai - Sepijoniskes road  bridge. right Gojus. In the river beaver dams. The current speed average. At the banks of the river forest.
32.3 left Buntiskes.
31.0 left Karve. left Paaukstoja.
30.6 right tributary. The river gradient increases significantly (up to Noreikiskes - Alsininkai road bridge about 900 cm / km), in the riverbed large stones, stream strong, shoals, rapids. Strainers less.
30.2 right tributary.
30.1 left Veršiukas.
29.5 Road ford. left Gerviskes.
28.3 left Juodupis.
28.0 right tributary.
27.1 left hillfort Noreikiskes mounds.
26.8  Road Noreikiskes-Medzionys  bridge. left Noreikiskes. right Kvedariskes. As we head towards the lake the river stream become calmer.
25.8 The Alsycia flows into the lake Alsia. Near the lake to the south  hillfort Piestuvenai.
24.7 Alsia flowing out of the Alsia lake. Average gradient to the mouth 132 cm / km. The river flows through the forest, strainers, rare small rapids, shallows.
23.7  Road Stakliskes - Kalviai  bridge. right Alsininkai.
22.8 Road ford.
20.7 right Virkius. Road ford.
20.5 Small bridge.
19.3 left tributary.
18.9 right Kamaine. right Kermosynas.
18.1 left Zelvis. left Azija.
17.7  Sundakai - Piestuvenai road  bridge.
17.5 right tributary.
16.6 left  Mulija.
15.6 right tributary.
13.4 left tributary. The river flows through the fields,  the banks overgrown with trees, bushes. Strainers less.
13.2 left tributary.
13.1 right tributary.
12.4 left tributary.
12.3  Road Sobuva - Stakliskes  bridge. right Sudvariskes. left Sobuva.
11.6 right Two small ponds.
11.0 right tributary.
9.1 Small bridge. left Bagdoniskes.
7.8 Road Trecionys - Bagdoniskis  bridge. Slightly upstream small bridge.
6.2 left Sulinga.
4.9 Small bridge.
4.5 Small bridge.
4.4 left Tauriekele.
3.7 Road Stakliskes-Trecionys  bridge. right Trecionys. A little bit downstream  starts channeled river stretch, the river flows through the meadows, strainers ends.
3.2 Small dam. Slightly upstream small bridge.
2.8 Small bridge.
2.5 left Meduja.
1.4  Vilnius - Marijampole road  bridge. right Pakrovai. Channeled river stretch ends, the river banks are overgrown with trees, may be some strainers.
0.7 right tributary.
0.0 The Alsia flows into the river Verkne.