The river Lakaja flows in Moletai and Svencionys districts, the river Zeimena right tributary. Length of the river 44 km, the basin area 433 km ². The source - flows from the lake Rudeselis, 6 km southeast from Moletai town. Flows through forests to the east and southeast through the lakes Rudesa, Baltieji Lakajai, Juodieji Lakajai, Aldikis and Lakaja. Flows into the river Zeimena 50 km from its mouth at Santakai village. Average gradient 39cm / km. The Lakaja has good groundwater supply, in the basin of rhe river is a lot of lakes and forests, its water level fluctuates slightly and runoff is distributed relatively evenly. Springs floods is not high (0.7-0.9 above summer water level) but lasts longer than in other rivers. Average rated discharge at Lakaja village (26 km to the mouth): max 11.2 m³/s, average 2.18 m³/s, min in summer 1.16 m³/s, min in winter 0.62 m³/s. Average rated discharge at the mouth 4.11 m³/s.

All year.
Low footbridges.
WW 0.

32.5 The Lakaja flows out from the lake Juodieji Lakajai. Average gradient to the lake Aldikis 48 cm/km. Cureent calm. The river meanders through forests. The riverbed width 7-12 m.
31.3 right Lakaja.
30.1 Zaugedai - Labanoras road bridge. Lakaja.
28.1 Wooden pedestrian bridge. right Palakaje.
27.5 Small bridge. left Azubaliai.
24.5 right Palakajis.
23.2 Low wooden pedestrian bridge. right Palakajis.
22.9 left the brook flows from the lake Guduniskis.
21.9 The Lakaja flows into the lake Aldikis. Area of the lake 22 ha, average depth 1 m. The shores swampy.
21.7 200 m length isthmus.
21.1 The Lakaja flows out from the lake Aldikis. Average gradient to the mouth 48 cm/km.
20.6 Svencioneliai - Zaugedai road bridge. Zukaucizna.
19.9 The Lakaja flows into the lake Lakaja. Area of the lake 74 ha, length 3140 m, max width 440 m. The shores mostly high, wooded.
18.5 right Kanele. left Baltagalis. right Kumeline. Isthmus.
17.7 The Lakaja flows out from the lake Lakaja.
15.5 right Moliai.
14.9 left Vilkaslastis.
13.8 Bridge. right Algirdiske.
11.8 Small pedestrian bridge. left Aukstasis Palakajys.
8.4 right Aukstoji Seskuske.
7.3 left Persoksna. right Aukstoji Seskuske.
5.5 left Zemoji Seskuske.
0.8 left Santakai.
0.0 The Lakaja flows into the river Zeimena.