Lake Onega water per year, of which 46% are industrial and household water, 25% is stormwater runoff and 16% is melioration-related drainage. This drainage contains of phosphorus and of nitrogen; respectively of these elements are removed through the River Svir whereas the rest accumulates in the lake. Ships and motor boats (about 8,000 units) bring oil pollution at the level of about per navigation year, as well as phenols (), lead () and oxides of sulfur, nitrogen, and carbon. The lake basin is a major source of granite, marble and black schist in Russia which have been exploited in the area since
Lake Onega of Karelia (about 270,000 citizens) founded in 1703 by Peter I to exploit the natural ore deposits. Petrozavodsk area contains a large number of historical monuments, such as Architectural ensemble Round Square (end of 18th century) and gymnasium building of 1790. The embankment of Lake Onega contains a series of sculptures, many of which were presented as gifts from the twin cities. Kondopoga is known from 1495 and contains the Uspenskaya (Assumption) Church built in 1774. This construction is one of the tallest wooden churches of the Russian North. There are two carillons in the city, with 23 and 18