The river Apascia flowing in Rokiskis and Birzai districts, the river Nemunelis left tributary. Length 88 km, the catchment area 893 km ². Source in swampy forest, 6 km to the southeast from Pandelis. Flows into the river Nemunelis 60 km from its mouth, at Nemunelio Radviliskis town. Riverbed width from the springs to Birzai 4-7 m, 10-20 m below. Depth  0,8-1.5 m, in rapids 0.2-0.7 m. Average gradient 70 cm / km. Spring flooding lasts for 20-30 days. Water rises from 1.5 to 2.5 m and to 1 m at the mouth.  Current speed in the summer 0.1-0.2 m / s in the spring to 1.5 m / s. Rated discharge at the mouth: max. 175 m³ / s avg. 5.0 m³ / s, min. 1.0 m³ / s. Riverbed from source to Simpeliskiai village channeled. Apascia valley near the mouth is a part of the Nemunelis - Apascia Geological Reserve.

All year, but not recommended in dry summer.
Shallows, rapids.
WW 0 (1+).

27.3 Dam. Bridge. Birzai. Astravas. Average flow rate about 2.5 m³ / s. Average gradient to the river Roveja 56 cm / km. The river flows through a meadows, banks low, in places overgrown with trees, sometimes naked. Riverbed width 15-25 m. Current is slow.
25.9 Pedestrian bridge. right Paezeriai.  left Rinkuskiai. Under the bridge small rapid.
25.7 Small rapid.
25.2 Pedestrian bridge.
24.5 right Draseikiai. Average gradient to the river Roveja 33 cm / km.
23.9 left hillfort Rinkuskiai. The river begins to meander.
22.5 right Roveja. Current is calm. Average gradient to the Uzusile channel  36 cm / km.
21.0 left Siline. left Jonava.
19.1 left Totoriai.
17.8 left A-3.
17.1 left Serbentiskis.
14.7 left A-1. left Bobeneliai.
14.3 right Uzusile. right Uzusiliai.
13.7 right the Uzusile channel. Average gradient to Kocenai 17 cm / km.
11.3 Small rapid.
10.7 right Aukstoji Gerve. right Kaseliskiai.
8.9 Pedestrian bridge. left Kocėnai. Average gradient to the river Zemoji Gerve. 43 cm / km. The current is little by little accelerating.
6.8 Pedestrian bridge. right Nausedziai.
6.7 right Zemoji Gerve. right Nausedziai. Average gradient to Nemunelio Radviliskis town 112 cm / km. The river width  about 15 m. The following banks are steep, current fast. To the mouth in the river rapids.
5.8 left Jasiskiai.
3.9 right Perkaso Gerve. right  Bliudziai. Begins Nemunelis - Apascia Geological Reserve. In few places on a banks dolomite outcrops.
3.3 Bridge.
2.7 right A-2.
1.3 Beginning of Nemunelio Radviliskis town. Average gradient to the mouth 231 cm / km.
0.6 On dam remains rapid.
0.5  Bridge. Nemunelio Radviliskis.
0.0 The Apascia flows into the river Nemunėlis.