Swamp waters are so - called bogs, hollows, streams and lakes, found throughout the marshes. The latter part occupy more than twenty percent of the area and mainly they are located in the south-eastern part of the Kola Peninsula. Swamp water can be distinguished by high composition of organic matter and ferric, acid reaction, a dark brown color, viscous form and unpleasant taste. According to the type of vegetation, feeding type and location marshes are divided into: flat, transition and high-moor bogs.
Flat or herbal bogs fed mainly by groundwater. Their ordinary location is met on the outskirts in overgrown lakes or in river valleys. High-moor or, in other words, moss bogs, mostly found in the watershed areas, are fed only by precipitation. Forest or transition bogs are fed by precipitation and groundwater. A small part of bogs has been drained. Nowadays it is used for agriculture.
Groundwater is contained in the pores of loose deposits. It is also called fault water. It can also be found in the cracks of crystalline rocks, so - called fissure waters. The depth of groundwater level vary from zero to several tens of meters, that depends on the subsidence level or mountains elevation. Water saturation zone of rocks lays vertically (from a few meters in loose cover up to several kilometers in crystalline basement).
In loose cover groundwater, as a rule, is free-flow, in crystalline basement it is pressure head. In this case the wall of inclined tectonic cracks serves as a confining layer. For this reason in the valleys scientists rather often observes water welling out from mining holes crossing tectonic cracks. However, in some places, such as the Khibiny valleys, you can also find in loose deposits pressure head waters where the confining layer is argillaceous deposits.
Groundwater is formed due to the atmospheric precipitation. Their movement is directed from the watersheds to the valleys where they are fed rivers and ponds, leaving the surface in the form of rills and dispersed flows. In winter, when water feeding of the atmospheric precipitation is absent, only the rivers and lakes feed groundwater.
Usually the speed of ground water flow is by one-two order less than that of lakes. It decreases with the depth increasing. At a depth of one-two kilometers water practically does not flow.
The temperature of the main mass of groundwater equal to just a few degrees. It increases with the depth under the influence of the earth heat and under the influence of the temperature of atmospheric air (only near the earth's surface).
Groundwater, as a rule, is mostly fresh, but it contain more dissolved salts than surface waters. Salinity of subsurface water increases with the depth. It contains one gram per liter or more at a depth of half a mile or two.
Groundwater is more various in chemical composition in comparison to surface waters. They are characterized by different proportion of ions concentration, high concentration of silica acid salts, low alkaline reaction. Waters of peat massifs are distinguished by a comparatively high content of organic matter, ferric, acid reaction, an unpleasant taste.
Natural resources, that is, the annual renewable groundwater flow area is equal to the average twelve cubic kilometers per year. It is about twenty per cent of the water resources of the region.
Forecasted usable groundwater resources that can be used for the water supply of the region, are estimated in two cubic kilometers per year. However, they are highly dispersed and their local resources are scanty. Therefore, they can provide cold water service for mainly small villages or small towns, though, if these waters be used only for drinking water supply, then it may be sufficient for even middle and large cities. Nowadays groundwater is used for water supply, but in a limited extent: their consumption is about four percent of the total water consumption for the water supply of the area.
Groundwater is not only valuable natural resource, but also a part of the geological environment, affecting on some types of economic activity - construction, field operation of solid mineral deposits. It is necessary to pump large quantities of groundwater from the trenches, underground mines, quarries, provide for other flow management measures.