The river Nieda flows in Alytus county, Lazdijai district, the river Baltoji Ancia right tributary. Length of the river 26 km, the basin area 297 km ². Flows out from the lake Zapsis, 8 km northwest from Veisiejai town. Flows through the lakes Veisiejis (to the lake calls the Zapse) and Niedus. Flows into the river Baltoji Ancia 26 km from its mouth at Kapciamiestis town. Average gradient 53 cm/km. Average rated discharge at the mouth 1.84 m³/s.

All year.
Strainers, low footbridges, water plants in summer, dam.
WW 0 (1).

32.7 Jurciunai. North side of the lake Galstas.
26.3 At the south side of the lake the brook (lenght 50 m) flows out to the lake Zapsis.
24.4 The river Zapse flows out from southern bay of the lake. Current average. The riverbed in some places overgrown by bushes, can be strainers, fallen trees. Average gradient to the lake Veisiejis 90 cm/km. The river width 5-7 m. right Kazeniai.
22.9 Bridge.
21.0 Bridge. To the Lithuania - Poland border 1,3 km.
19.7 Bridge. left Pazapsiai. right Kalediskiai.
18.6 right Briniai. The river flows through forest. Can be strainers, fallen trees.
16.7 Bridge. The river flows through meadows.
16.1 The Zapse flows into the lake Veisiejis. Keep left shore.
15.3 Bridge.
14.4 Turn to south. Small island. left hillfort Paveisininkai. Under water can see old road.
12.7 left Paveisininkai. right Sapiegiskiai. To Kapciamiestis town at the shores of the lakes forests.
9.3 left Burbai. left the brook from the lake Uosis.
7.7 right Gerveliai. right narrow peninsula.
6.7 The lake Veisiejas at southern side connect the lake Niedus. right Subaciai.
5.9 right Kalviai. right the brook from the lake Kaviskis.
4.4 left Purviniai.
3.3 The Nieda flows out from southern side of the lake Niedus. Current calm. Kareivonys.
0.8 The dam of Kapciamiestis HPP. Portage better right. Kapciamiestis.
0.05 Bridge.
0.0 The Nieda flows into the river Baltoji Ancia.