Surface waters of the Polistovsky Reserve are represented by rivers, lakes and vast bog tracts. The major rivers are Lovat and Polist; the territory of the Reserve is located between these rivers. River Lovat has rapids in some places; its banks rise to 11 m, the channel's width is 35-140m, the depth at shoals and rapids makes 0.2-1m, on stretches - 1.5-2.5m (maximum - 4.3m). The rate of flow of river Polist is 0.1-0.3 m/s; the width of the river is up to 20 m, the depth is 0.3-2 m.
By virtue of a plain relief of Polistovsky Reserve and unexpressed riverbeds, the draining role of rivers is negligible. By regime, rivers of the area belong to the Eastern European type mainly with snow feeding. All the rivers are characterized by a spring flood in late March - the first half of April; in autumn a slow rise of water levels from rain begins. The height of autumn floods, is usually lower than spring floods. The autumn rise of the level continues until first ice formations on the river. On boggy rivers of Polistovsky Reserve (Redya, Polist) the summer-autumn runoff is usually high and amounts to 30-39% of the annual runoff. All the rivers have low banks and meandering channels.
Rivers. A characteristic feature of the Polistovo-Lovatsky wetland massif is the abundance of medium-sized rivers, streams and lakes. By morphological features, marshy rivers of Polistovsky Reserve belong to three types:
- open rivers (open channel)
- buried rivers flowing inside peat deposits
- undermoss, or blind rivers flowing under the moss.
Same rivers rarely keep the same morphological character along its entire length. They are much more likely represent a combination of different types of channels, often with alternating sections of different ages. Marsh streams are thus complex rivers.
Lakes. The Polistovo-Lovatsky massif has up to 20 large lakes; within Polistovsky Reserve all lakes are located in groups. The Northern Group consisting of three lakes - Russkoye, the second largest (390 hectares), and Mezhnitskoye and Kokorevskoye - is within the Polistovsky Reserve.
Lakes of the Polistovo-Lovatsky massif, usually as well as all lakes of raised bogs, belong to the group of paraoligotrophic reservoirs (Bogdanovskaya-Giendef 1969); they are characterized by water poor in calcium and high in humic substances. In most cases, lakes are located in hollows of the surface, which reflect the lowering of the bottom (Russkoye, Mezhnitskoye, the southern group of lakes). The depth of the depressions reaches 1.5-2 m (Lake Russkoye). In more rare cases, lakeshores are flat (as in lake Kokorevskoye).
Stratigraphy of lake sediments of Polistovsky Reserve is often different. The water depth varies between 1 and 2.5 m, growing along the eastern coast. Sapropel humus forms a false bottom. Usually under these deposits there is a layer of thin detrital sapropel (from 0.25 to 0.6 m thick). Clay sapropel is located lower; there is no such sapropel in lake Russkoye, and in other lakes the capacity of clay sapropel is from 0.2 to 0.7 m.
Lakes are of great importance as intakes. Their draining influence has a strong impact on surrounding parts of the bog. Parallel to the coast of some lakes there are unique, long, sometimes meandering lakes, or hollow lakes. The depth of water in these lakes is up to 2.5-3 m.
A special feature of bog lakes of Polistovsky Reserve, which is probably a consequence of their feeding mainly with groundwaters of the peat land, can be the constancy of the level of water in such lakes during the year. In lake Russkoye, water in the summer is lower than the shore level only by 20-25 cm; in other lakes, the height of shores above the water level is 30-40 cm.
Lakes of the southern group, in contrast to the northern one, together with the coast erosion, one can observe overgrowth in shallow bays, especially on the western side (Potamogeton, Potbelly yellow).
Lakelets. The Polistovo-Lovatsky massif has a great number of lakelets scattered among the moss cover, but they are distributed very unevenly: some parts of the massif have no lakelets at all, whereas in other parts of the massif they form a very distinctive and essential part of the landscape.
The origin of lakelets can be divided into two main groups: primary (residual), remains of former lakes or streams, and secondary, formed during the development of peat. There are transitions between these two groups: some lakes are remnants of rivers flowing from the bottom of the peat, while others, being primary ones, are limnological peat deposits.
The major part of Polistovsky Reserve is occupied by a raised bog, borders are covered with transitional sphagnum, shift and scheuchzeria-sphagnum swamps. Raised bog biogeocenoses are divided here as follows. Pine-moss corp-sphagnum areas are generally weakly distributed: in places with a small capacity of peat deposits. A ridge-hollow complex occupies the largest territory. It is presented by various options, from sites with well-defined stripes pine of form litwinowii 3.5 m high to open areas without pine - so-called 'scrapers'. Ridge-bog complexes of primary and secondary lakelets usually have a small area and they are locally mainly in eastern, southeastern and northeastern parts.
Groundwaters of the Polistovsky Reserve are represented by inner deposit water in the bulk peat: buried water bodies, water intrusions, water veins and interlayers.
By hydrochemical characteristics, all water bodies and watercourses of the Polistovo-Lovatskaya raised bog system can be considered poliygummatous, soft-water with an acidic pH, poor in iron and calcium, which is caused by the catchment area occupied mainly by bogs. Average hydrochemical indicators are: pH 4.2 - 5.5, total hardness 0.08 - 0.28 mEq/L, dissolved oxygen 12.1 - 8.8 mg, permanganate oxidation of 69.8 - 55.7 mgO/l.