Lake Nero

Lake Nero () is a shallow, highly eutrophic lake in Yaroslavl Oblast, Russia. The lake has an area of 54.4 km², a maximum length of 13 km, width 8 km and depth 3.6 m. The bottom of the lake is covered with thick layer of silt sapropel (a sort of ooze used as fertilizer and for other purposes).
The lake is estimated to be about 500 thousand years old, making it one of a few pre-ice age lakes in central Russia.
The first people settled at the lake 6 thousand years ago. It is historically certain that the Merya tribe had their capital in Sarskoe Gorodishche on the southern shore of the lake. They named the lake "Nero" (meaning "silty", "marshland") or "Kaovo" ("place where gulls live").
In the 9th Century East Slavs came to the lake. They called the lake "Rostovian Lake" in the honor of town Rostov.
There are two significant islands, "Lvovsky" (Львовский, " Island"), also known as "Lesny" (Лесный, "Forest Island"), and "Rozhdestvenskij" ("Рождественский", "Christmas Island"), also known as "Gorodskoj" ("Городской", "Town Island"). The latter formed a pre-ice age monolith.
The eight rivers that flow into Nero Lake are
(), Ishnya (), Kuchibosh (), Mazikha (), Varus (), Chucherka (), Unitsa (), Sula () etc.), one flows out (Veksa ()).
Near Nero Lake is located the town of Rostov (on the western shore of the lake) and a few villages (on perimeter): Porech’e-Rybnoe (), Ugodichi (), Vorzha (), L’vy () etc.
The first steamboat "Emel’yan" () appeared on the Lake in 1883.