On the bank of the Angara River, 68 km from the Irkutsk ostrog, a detachment of Yenisei Cossacks led by Anisim Mikhalev discovered a salt spring. In the register of land allotments of the Irkutsk ostrog for 1669, it was recorded that the Cossack commander of fifty, A. Mikhalev, “by decree of the great sovereigns,” was granted “salt works on two small islands on the right side, and land on the large island. And opposite those same islands, going upstream along the left side, above the Belaya River and below the Kitoy, in a meadow among stones, above and below, for arable land 30 desyatinas, hayfields 40 desyatinas.”
Salt production was mainly carried out by A. Mikhalev’s elder brother Gavriil and his sons. In 1682, after Gavriil’s death, the operation was sold to the Irkutsk merchant Ushakov. Usolye was managed chiefly by the Ushakovs’ steward Ignatiy Yurinskiy. In 1704, the springs were transferred to the ownership of the Ascension Monastery (Irkutsk). The monastery owned them for more than 60 years. Then the salt works were placed under state administration. At that time, the islands and banks were covered with virgin forest.
Salt springs had been known to people since deep antiquity.
Excavations and bank washouts of the Angara River have established that salt production in these places was carried out as early as the Bronze Age.
On Varnichny Island, five salt springs were recorded, known as: Petropavlovsky (the strongest and most abundant brine), Bolshoy and Maly Alexandrovsky, Ilyinsky, and Voznesensky.
Only by the beginning of the 20th century were geological studies of the salt springs conducted in a sufficiently comprehensive scope, making it possible to conclude that the reserves of mineral waters in the Usolye District were practically inexhaustible.