63 Himalayan Geology, Vol. 29 (1), 2008, pp.63-72, Printed in India Water chemistry of three Himalayan Lakes: Dal (Jammu & Kashmir), Khajjiar (Himachal Pradesh) and Nainital (Uttarakhand) R.K. SAINI 1 , S. SWAIN 1 , A. PATRA 1 , G.J. KHANDAY 2 , H. GUPTA 1 , P. PURUSHOTHAMAN 1 , G.J. CHAKRAPANI 1 1 Dept. of Earth Sciences, Indian Institute of Technology, Roorkee - 247667 2 Dept. of Geology and Geophysics, University of Kashmir, Srinagar Email: gjcurfes@iitr.ernet.in Abstract: A comparative study of major elements composition (Ca 2+ , Mg 2+ , Na + , K + , HCO - , SO 2- and Cl - ) and nutrients (PO 3- , NO - , SiO 2 ) of Dal Lake (Jammu & Kashmir), Khajjiar Lake (Himachal Pradesh) and Nainital Lake (Uttarakhand) situated in the Himalayas is discussed in the present work. All the three lakes are important tourist destinations and are characterized by varied lithology and land use. High total dissolved solids, electrical conductivity, bicarbonate, sulfate and nitrate concentrations in the Nainital lake and the Dal lake reflect anthropogenic inputs in the form of sewage from surrounding areas, houseboats, hotels, etc. Total dissolved solid (TDS) concentrations are high in Nainital Lake followed by Dal Lake and Khajjiar Lake. The major ion chemistry of all the three lakes is dominated by carbonate source rock weathering. The lakes are characterized by high nutrient concentrations. Water quality index (WQI) determined for two of the lakes (Nainital and Dal) indicate high pollution index. The samples were collected during one season and hence the discussion pertains to the period of sampling only. INTRODUCTION Increased anthropogenic impact on surface water systems result in high pollution loads, such as phosphorous and nitrogen compounds, heavy metals, agrochemicals etc., which cause rapid deterioration in water quality. Lakes are relatively less dynamic and hence are easily vulnerable to exogenic inputs and accumulate pollutants with time. The lake water derives its composition from the reaction of atmospheric precipitation with the country rocks and additional inputs from other sources such as river/ spring water, industrial disposal of solid/ liquid wastes etc. Lakes are very aesthetic and hence attract tourists from far and wide. The lakes do not sustain themselves for long time scales, since rapid sedimentation and eutrophication are enhanced due to human activities. Three such lakes in the pristine Himalayas are the Dal in Jammu and Kashmir, Khajjiar in Himachal Pradesh and Nainital in Uttarakhand. All these lakes are a source of livelihood for the local habitants and hence in order to assess the pollution status in the lakes in the present study, we focused on the lake water compositions and possible contaminations. STUDY AREA The Dal Lake (Fig. 1A), which is the second largest fresh water lake (in Jammu and Kashmir State), is located to the NE of Srinagar city (34°18’N & 74°91’E) at an altitude of 1584 m above mean sea level (MSL). The total water surface of the lake is 11.45 km 2 of which 4.1 km 2 is under floating gardens, 1.51 km 2 under land and 2.25 km 2 under marshy conditions (Trisal 1987). The lake comprises a myriad of inter-connecting channels and is divisible into four major sub-basins, viz., Hazratbal, Bod-dal, Gagribal and Nagin (Singh & Sharma 1999). It is fed mainly by a large perennial inflow channel, Telbal nala, which drains a large sub catchment area of about 145 km 2 and contributes about 80% of the total inflow to the lake (Zutshi & Vass 1978). The Nagin basin is the deepest basin (maximum depth being 6 m) and Gagribal basin is the shallowest (maximum depth 2.5 m). Water from Telbal nala and other streams enters the lake from Hazratbal basin, passes through Bod-dal, Nagin and Gagribal basins before entering into the river Jhelum. The total area of the Dal Lake catchment is about 314 km 2 , which is about twenty five times more than the lake area. The saucer shaped Khajjiar Lake (Fig. 1 B) is located in the Chamba district of Himachal Pradesh (25 km from Chamba and 23 km from Dalhousie). It is fed predominantly by groundwater followed by limited runoff and precipitation. These sources of water drain through rocks that are rich in silicates and carbonates. The lake is a part of Kalatope reserve forest and is surrounded by forest of Cedar (Deodar) plants. This small lake rests in the center of the large glade of Khajjiar, at approximately 1900 meter above the mean sea level and the entire catchment is located between latitude 32° 26’N and longitude 76° 32’E. Nainital Lake (=Naini Lake) (Fig. 1C) is situated approximately 1937 meter above the mean sea level in the district of Nainital of Kumaun Himalayan region in Uttaranchal, at the intersection of latitude 29º 24’N and longitude 79º 28’E (Sharma et al. 1982). It is one of the most frequented tourist destinations of the Kumaun Himalayas. The lake is in a wide crescent shape. The lake bed essentially comprises of two- 4 3 3 4