Lake Polisto was declared a monument of nature of the Pskov region by the Decision of the Executive Committee of the Pskov Regional Council of People's Deputies of 29.01.1976. No 46 (p.1., Annex № 2 'About taking monuments of nature under protection'). However, the legal status of the monument was not determined: no boundaries were defined, no plots were allocated, there was no taking under protection, and there were no even materials about the value of natural objects of the lake and its surrounding areas. Therefore, this decision of the executive committee together with other decisions was recognized invalidated by the decree of the Administration of the Pskov region of 10.10.2007 No 391.
In 2006 the Administration of the Polistovsky Reserve in conjunction with the State Committee of the Pskov region on Licensing and the Environment Use began the work on preparing the full set of documents required for the creation of a monument of nature under the current legislation (Annex 2 to the Order of the Administration of the Pskov Region on 15.06.2004 No 250). Now the work came to an end: a draft monument of nature is defined and its borders are described, a comprehensive pilot survey of the territory is conducted, and documents substantiating the uniqueness of nature are prepared. Finally, on December 20, 2007 the future nature monument has passed the State ecological expertise; on July 23, 2009 the Governor of the Pskov region A.A.Turchak has signed Decree No 277 'About the Nature Monuments of the Pskov Region 'Lake Polisto'. So now one can consider this date the birthday of the Monument of nature. The same decree has also approved Regulations on Natural Monuments where its which regime was described. You can view the two documents on this page.
What is unique in this lake?
Lake Polisto among numerous reservoirs of the Pskov region occupies the fourth place by size (area 3160 ha). It is the largest reservoir of the largest in Europe Polistovo-Lovatskaya bog system having international environmental significance. The basin of the lake is slightly elongated from north to south; the length is about 10 km, the maximum width is 7 km, the average depth is 1,5 m.
This is a flowage lake. Rivers Osyanka and Tsevla flow into the lake; the latter arises from lake Tsevlo. River Polist flows from the lake and flows into lake Ilmen. Lake Polisto is of a residual origin; it was formed at the site of an ancient lake-glacial lake. The bottom of the lake is leveled, sand and rocky, with muddy places. The shores of the lake are low, marshy, indented, the shoreline is rugged relatively weak. According to hydrochemical characteristics, lake Polisto can be considered polygummatous, soft-water reservoir with slightly acidic pH, due to the catchment area that is occupied mostly by raised bogs; the water is poor in iron and calcium. According to the trophic status, at this stage of development lake Polisto can be considered water bodies of mesotrophic type with signs of dystrophization.
The lake has poorly developed submarine vegetation and medium-developed air-water vegetation. The shoreline coastal is covered mainly by reed and bulrush, amphibious knotweed; reed baldingera grass prevails in the estuary of river Tsevlo and source of river Polist. The lake's phytoplankton by the quantitative indicators (number of species, abundance and biomass) is represented by diatoms, green and blue-green; the latter form of up to 7% of the biomass and cause blooming of water. The basis of zooplankton is cladocerans and copepods. In terms of quantitative indicators, the summer zooplankton in the lake can be considered mid-fishfood type, i.e., conditions for the feeding of young fish and planktophagous fish are satisfactory.
According to the ichthyofauna composition, the lake is attributed to a breem-zander. The lake is home to perch, pike, zander, bream, bleak, silver bream, sabrefish, zope, roach, rudd, ide, burbot, catfish. From the ichthyological point of view, dwelling of sabrefish and zope in lake Polisto can be interesting. And if zope can be rarely found in Pskov lakes, then sabrefish can be observed in lake Polisto only. In the shallow waters of the lake there are spawning grounds for many fish species, including bream, perch, roach and pike.
ased on previously obtained data and materials of the research carried out on lake Polisto during the existence of the Polistovsky Reserve one can emphasize the exceptional natural value of the water body to maintain the hydrological regime, preservation of landscape and biodiversity not only of the Pskov region but also of the North-Western region of Russia as a whole. The Polistovo-Lovatskaya bog system, the largest water body of which is lake Polisto, has an international conservation importance in accordance with the program 'Thelma' (UNESCO). The territory of the Polistovo-Lovatskaya bog system, which is the catchment of lake Polisto and river Tsevla, is a promising list of wetlands of the Ramsar Convention (Ramsar Shadow List). Also, this area is an important reserve for migratory birds, protection and study of which lays within the scope of the Bonn Convention, as well as the International Agreement on the Protection of Migratory Afro-Euro-Asian Waterbirds (AEWA). he catchment area of the lake is occupied mainly by bogs; river Tsevla and about a dozen of small rivers and streams flow into the lake, consequently, lake Polisto is a reservoir of pure low-mineralized water. River Polist flows from the lake and carries its waters into lake Ilmen - one of the largest reservoirs of the North-West Russia - the Baltic Basin, with a great economic significance. Thus, one can clearly understand the importance of the lake Polisto and its catchment area to maintain the hydrological regime of adjacent areas.
Undoubtedly, the lake Polisto, river Tsevla and water meadows and shores have great importance to maintain the natural biodiversity of the Pskov region. It is worth noting the special faunal value of this natural area. The lake is home to 15 species of fish, including two rare species in the region. Lake Polisto is the only reservoir of the Pskov region, which inhabits sabrefish ('freshwater herring'), and one of few bodies of water area, inhabited zope. Shallow areas of lakes are breeding grounds of many fish species, including bream, perch, roach and pike. In the upper reaches of river Polist burbot is spawning; this is also the place for one of the few remaining in the Pskov region populations of crayfish.
This water body is an especially valuable nesting and migratory spans area for many types of waterbirds and semi-aquatic birds. This is home to white-tailed eagle, osprey and Greenshank - species listed in the Red Book of Russia and the IUCN, and also to about twenty regionally rare bird species, protected in the Baltic states, Belarus and regions of the North-West Federal District. On the flood plains along Lake Polisto and the mouth of river Tsevla there were discovered two new species of birds for the Pskov region.
On the shores of Lake Polisto there were discovered a unique community of rare plant species. During the inventory of flora coastal areas researchers from the Tsitsin Main Botanical Garden of RAS and the Komarov Botanical Institute of RAS found rare plants for the Pskov. For example, fern - Botrychium partitioned, Orchidaceae Morio marsh, requiring ultra-pure water waterwort, or water pepper. Many rare and ornamental plants - Gentiana pulmonary, Violet persicifolia, Trostyanka ovsyannitsevaya (blowout grass) grow along the shores in large quantities, and peat shoals on the north shore of lake Polisto and the mouth of river Osyanka were allocated to the category of botanical phenomena. Thus, the abovementioned allows us to suggest the multifaceted uniqueness of lake Polisto as an integrated Nature Monument of the Pskov region.