The lake has 17 species of fish, such as minnows, salmon, chubs, eels, and pike, and there are areas for duck hunting.

The banks are shallow and sandy, but along the southern coast, waves have carved sandstone cliffs.

After the regulation of the Salaca river in 1929, the lake level dropped by a metre, and many of the exposed shallows grew covered with reeds and algae.

Lake Burtnieks is the source of 95 km long Salaca river, which flows out of the northwest corner into the Gulf of Riga.

In ancient times, the lake was known as Astijärv or Aster, when northern Vidzeme was inhabited by the Livonian people.