State Nature Reserve "lousy Lake", located 3 km southeast of the village Demino (Shpakovsky district), on the border of river basins and Grachevka Egorlyk is a natural terminal lake Stavropol Upland. The reserve, with a total area of ​​about 259, 45 hectares, is located at an altitude of 505 m above sea level. The lake is very old, he was more than a million years.

Renowned scholar and ethnographer V. Gnilovskaya links the name of the lake with an abundance of insects that live near the surface of the water - water fleas, water striders, cyclops, and others. According to the Russian scientist, public figure and ethnographer Grigory Prozriteleva originally it was called Ushy that translates from the Tatar - "three". That's called Tatars found near the cross, which was placed by the ancient Christians.

The researchers who conducted the monitoring of the lake in recent years, noted that the 50-ies. The twentieth century it almost dries up in the summer and turns into a muddy swamp overgrown with reeds. In 1995, after heavy rains the water level in the lake rose enough. Fluctuations in the volume of water in the lake has led to a change in its natural fauna.

The reserve is home waterfowl such as water hen, bittern, snipe, stilt and coot. The usual reeds marsh harrier. Also is home to marsh frogs, turtles, leeches and water snakes. On the flight here always stop swans. Of fish in the lake are found carp, carp and carp. In the bottom sediments of the lake are the nitty burial spores and pollen of plants that grow in the areas adjacent to the lake during Holocene and Pleistocene.

Total in the reserve "lousy Lake" There are 25 types of meadow and marsh plants, among which are 8 species of sedges (false sulfuric, early, coastal, pigweed, yachmeneryadnaya, hairy, obtuse and chernokolosnaya).