The river Perseke flows in Alytus county, Lazdijai and Alytus districts, the river Nemunas left tributary. Length of the river 66 km, the basin area 542 km ². The source at Gervenai village, 2 km northeast from Seirijai town. Flows to north through the lake Obelija, below turns to north west through the lake Paupiai, from Gluosninkai village flows to northeast. Flows into the river Nemunas 318 km from its mouth at Balbieriskis town. In upper section to the river Metelyte mouth calls the Obelyte. The riverbed width in upper section 3-5 m, downstream 6-8 m; depth 0.5-0.8 m. Average gradient 120 cm/km. The banks overgrown by alder, willow bushes. The valley width 200-300 m; slopes height 9-12 m. Spring floods short and sudden; in lower section the river water rises up to 3 m. Speed of current 0.2-0.4 m/s. Average rated discharge at the mouth 3.6 m³/s.

At higher water level. Spring, or after heavy rains.
Rapids, shalows, dam, strainers.
WW 0/1 (2).

23.7 Udrija - Krokialaukis road bridge. right Perseke. Current calm. The river flows through meadows. On the banks bushes. Can be a few strainers. The river width to the mouth 5-8 m. Average rated discharge 2,11 m³/s.
23.6 right Karputys. Average gradient to the brook Rude 86 cm/km.
21.7 left Ziuronys.
19.2 left Rude. left Sukuriai. Average gradient to the brook Kamaria 76 cm/km.
17.8 Bridge. left Pramezys.
17.1 left Kamaria. right Mackiai. A bit downstream, in the river loop right Pramezys manor and park. Average gradient to the brook Vaiciukupis 112 cm/km. Current fast. A few strainers.
16.2 right Gulbe.
14.6 left Vaiciukupis. left Zagariai. Average gradient to the brook Rude 95 cm/km.
11.6 Balbieriskis - Udrija road bridge. right Keliskis. left Putrisiai.
11.3 On site of the dam of former Putrisiai watermill 0,5 m height rapid. Navigable on middle.
11.1 right hillfort Kieliskas. To Kelmanoniai village the riverbed narrow, current fast, many strainers.
8.7 right Rude. left Rudziakampis. Average gradient to the mouth 130 cm/km.
7.8 right the brook P-4.right Kelmanonys. The river meanders between hills. Current fast. In some places small rapids.
4.3 right Kiziai.
3.6 right the brook P-2. Current calms.
3.4 Bridge. Balbieriskis.
3.2 On the dam site of former Balbieriskis HPP 2 stages rapid. 1st stage approx 0.5 m height drop, width of the river approx. 15 m. 30 m dowstream, at turn 2nd stage - current accelerated, few drops. Below the rapid current fast, small rapids.
2.6 Country road ford. left Balbieriskis park.
1.2 Small bridge.
0.8 Steel bridge.
0.3 left Dume. A bit downstream Alytus - Prienai road bridge. Current calms.
0.0 The Perseke flows into the river nemunas.