4.1 STUDY AREA: Greater Bangalore (77°37’19.54’’ E and 12°59’09.76’’ N) is the principal administrative, cultural, commercial, industrial, and knowledge capital of the state of Karnataka with an area of 741 square kilometers and lies between the latitudes 12°39’00’’ to 131°3’00’’N and longitudes 77°22’00’’ to 77°52’00’’E. Bangalore is located at an altitude of 920 meters above mean sea level, delineating three watersheds: Hebbal, Koramangala - Challaghatta and Vrishabhavathi watersheds (Ramachandra and Kumar, 2008).

Ulsoor Lake is one of the well known historical lake in the city,  located in the eastern part of Bangalore, in the Challaghatta Valley covering an area of 41.5 hectares (reduced from 50 hectares). Current depth of water is 1.5 m (earlier depth was 5.6 m) and is fed by Munireddy Palya drain and Doddakunte drain, the outlet is through Gurudwara Challghatta main SWD to Bellandur tank (Randhawa and Bharmal, 2010).

Figure 2.1: Sampling points at Ulsoor Lake
Ulsoor lake	S1- Inlet to the lake
S2	S3
S4	S5
S6 – Outlet of the lake	Fishes at the outlet of Ulsoor lake
Plastic wastes and Organic waste floating at the surface of Ulsoor lake
Sewage water flowing into Ulsoor lake		Solid wastes at the outlet of Ulsoor lake
Figure 2.2: Field conditions at various sampling locations
Massive fish mortality at Ulsoor lake

Figure 2.3: Dead fish in Ulsoor lake

4.2 ANALYSIS OF PHYSICO-CHEMICAL PARAMETERS: Water samples from six different sites were collected on 7th March, 2016 for water quality analysis of Ulsoor lake (sampling locations are marked in figure 2.1 and figure 2.2). The water temperature, pH, electrical conductivity, TDS and DO were determined on spot at the time of sampling. Other parameters like nitrate, orthophosphate, turbidity, total alkalinity, calcium and magnesium hardness, total hardness, chlorides, COD, BOD, sodium and potassium were analysed in the laboratory as per standard protocol (Trivedi and Goel,1986 and APHA, 1998). Table 3 lists the methods adopted for estimating various water quality parameters. Figure 2.3 depicts large scale fish mortality, which highlights the gravity of the contamination. 

Table 3: Standard methods followed for water quality analysis

4.3 PHYTOPLANKTON AND ZOOPLANKTON ANALYSIS:

Plankton collection and Identification: Plankton samples were collected by filtering 50 litres of lake water through the standard plankton net (No. 25 bolting silk cloth net of mesh size 63 mm and 30 cm diameter). The final volume of the filtered sample was made to 20 ml and then transferred to another 125 ml plastic bottle and labeled, mentioning the time, date and place of sampling. The samples collected were preserved by adding 2ml of 5% formalin. Samples of phytoplankton and zooplankton were identified through microscope using the standard keys and interaction with experts.