Sandimirov S.S. Catalogue of lakes in the Russian, Finnish and Norwegian Border Area. Finland, Jyvaskyla: Kopijyva Oy, 2008.

1.19 LAKE KUETSJARVI Lake Kuetsjarvi (watershed of the Riv­ er Paz) is located at a distance of 3 km from the Russian-Norwegian border, and close to the town of Nikel. Lake Kuetsjarvi is one of the largest lakes in the Russian border area of (area of the lake 17.0 km2).The lake is relatively deep (maximum depth 37 m), of elongated shape, and of glacial origin. The maxi­ mum length is 11.6 km and maximum width 2.8 km. The point of maximum depth is located in the northern part of the lake, where the depths are significant near the shore. In the central part of the lake the maximum depths reach 10 m.The south­ ern part of the lake is shallow, with a maximum depth of 12 m. The lake belongs to the lake-river system of the Paz River, to which it is linked by a small stream. According to the landscape type, the watershed consists of a combina­ tion of flat, low-lying areas of glaciolacustrine flatland, and denudation and denuda- tion-tectonic massifs with abrupt outcrops of quaternary deposits with a height of up to 631.0 m (Kuorpukas fell). The lake shores are high and covered with pine forests and scree. As a result of mining and excavation over a huge area, the natural landscape is seriously damaged and the fell tops levelled and the orography changed. The water of the lake is colourless but, during flood periods and episodes of high precipitation, the water colour in the southern part of the lake, where the River Shunijoki enters, increases to SOdeg. and becomes yellowish. There are some boulder beds and sandy beaches (mostly in the southern part) in the littoral zone. The gaps between the boulders are filled with sand and pebbles. Dark green silt deposits predominate in the northern, less polluted part of the lake. In the southern part, where effluent from the Pechenganikel smelter flows into the River Kolosjoki, the silt deposits are almost completely black. 1.19.1. Hydrochemistry The lake is one of the most polluted lakes in the Pechenga region. The industrial com­ plex, located on its shore, poses a serious threat to natural aquatic environments in the joint Norwegian, Finnish and Russian border area. Granulated waste material, produced in connection with metal production at the smelting plant, has been dumped along the shore of the River Kolosjoki. Toxic compounds are leached from the slag heaps by rainwater, snowmelt and surface runoff. Dust from the slag heaps also has a very severe impact on the environment. Wastewater is discharged directly into the water body. The water of the lake is neutral and has a total mineralization of 69 mg/l and aver­ age alkalinity of 286 |_ieq/l. During flood periods the pH falls to 6.71 and then rises back to 7.31. The lake has high concentrations ofbase cations and anions, with calcium (average 10.2 mg/l) and sulphate (average 28.9 mg/l) predominating. Severe pollution of the lake occurred during the period of peak emissions from the “Pechenganikel”smelter in the late 1980s and early 1990s. Maximum concentrations of most elements, especially sulphate (up to 40.3 mg/l), Cu and Ni, were recorded Physico-geographical characteristics River Paz Latitude 69°26.052' Longitude 30°09.447' Height above sea level, m 21.3 Maximum length, km 11.6 Maximum width, km 2.8 Maximum depth, m 37 Area, m 2 17.0 Watershed area, km 2 628.4 Study period 1994-2007 Catalogue ofLakes in the Russian, Finnish and Norwegian BorderArea