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

2.2. LAKE ELLENTJA Lake Ellentja (watershed of the River Paz) is located 53 km to the south-west of the town of Nickel. The oval-shaped lake is not large (area of the lake 1.06 km2) nor deep (maximum depth 10 m), and is of glacial origin. The maxi­ mum length is 1.7 km and maximum width 1.17 km. The points of maximum depth are located in the central part of the lake. The lake is the most downstream in the lake-river system of the River El- lenelva. According to the landscape type, the watershed belongs to the forest zone, with heights of up to 260 m. The lake- shores are low, waterlogged, and covered by shrubs and pine forest. 2.2.1. Hydrochemistry The pH in the water of the lake is close to neutral and has low total mineraliza­ tion (average 14.2 mg/l) and alkalinity (average 105 |aeq/l). During floods pe­ riods the pH drops slightly, i.e. oxida­ tion processes do not develop due to the buffering capacity of the water. The lake has low concentrations of base cati­ ons and anions, with calcium (average 1.53 mg/l) and bicarbonate (average 6.4 mg/l) predominating. The annual chemical cycle of the lake is characterized by a slight reduction in the oxidizability and pH of the water during flood periods when the amount ofprecipitation and inflow of humic wa­ ter increase. The concentrations of P and N are important criteria when estimating wa­ ter eutrophication. The concentrations of and relationships between species of P and N vary according to the season, and the dynamics is to a greater degree determined by the level of production and, consequently, the trophicity of the Watershed River Ellenelva— River Paz (Tjerebukta) Latitude 69°12.568' Longitude 29°07.094' Height above sea level, m 71.0 Maximum length, km 1.70 Maximum width, km 1.17 Maximum depth, m 10 Area, km 2 1.06 Watershed area, km 2 187 Study period 2002-2003 Hydrochemical properties pH 6.65 6.55-6.80 Electrical conductivity, mS/cm 23 22-26 Ca, mg/l 1.53 1.41-1.77 Mg, mg/l 0.58 0.55-0.65 Na, mg/l 1.52 1.46-1.61 K, mg/l 0.43 0.41-0.48 HC03, mg/l 6/4 6.0-7.1 S04, mg/l 2.20 2.07-2.37 Cl, mg/l 1.53 1.36-1.77 Total mineralization, mg/l 14.2 13.3-15.8 Alkalinity, |jeq/l 105 98-117 Water colour, deg. 16 12-18 nh 4, мд/і 12 6-15 N03, цд/І 2 1-2 Total N, |jg/l 183 176-195 P04, мд/і 1 1-1 Total P, мд/І 4 4-5 water body. The average concentrations of total P and total N during the vegetation period are 5 (ig/1 and 195 [ig/1, respectively. Catalogue o f Lakes in the Russian, Finnish and Norwegian BorderArea