Big Ludzas Lake is located on the edge of the Latgale upland, in Zvirgzdene parish of Cibla municipality and by the eastern border of Ludza town. It is 132.8 m above sea level.

The lake has a stretched form and narrows in the middle. There are coves, peninsulas, 4 island. The shores are low. The bottom is sandy. It is a running-water lake. The Pilda, the Istalsna and streams from Small Ludzas Lake, Dūnākļa Lake and other neighbouring lakes flow in to Big Ludzas Lake, it is also fed by several ditches and channels. The Ludza River flows out of the lake. There are breams, sanders, roaches, perches, pikes.

Area: 8.46 km2, area with islands 8.51 km2

Length: 7.0 km, max. width: 1.9 km.

Average depth: 3.5 m, max. depth: 6.5 m.

Basin: 473.5 km2 (it belongs to the basin of the Velikaya River)

 

Latvijas daba. 3.sēj. – Rīga: Latvijas enciklopēdija, 1995. – P.123.

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