Cauvery River is the major river system of south India was studied for 19 prime physicochemical and 2 bacteriological parameters at six locations of the Kollegal stretch, for a period of Two years (2006)(2007)(2008) at monthly intervals. Over the years of time, river has been subjected to human interference regularly and water quality was to be getting deteriorated profoundly. Major anthropogenic activities practiced in and around the stretch: agriculture, abstraction of water for irrigation and drinking, washing cloths and utensils, discharging of sewage waste, sand dredging, boating, fishing, open defecation and religious ritual activities along the stretch were generating serious threat to the biota of the river by altering the physicochemical and biological concentration of the river system. The seasonal and yearly trends were discussed to comprehend anthropogenic interferences on the river stretch. Correlation analysis was also been tried in between physico-chemical parameters. The pH, Conductance, Alkalinity and Hardness levels indicate the moderate quality of water. The values of DO, BOD and COD levels indicate the absence of major organic pollution sources. Seasonal and yearly averages of plant nutrients like phosphate, nitrates, potassium and also sulphates at drain out falls and mixing zones, were not showing any significant variation in their concentration indicate no sign of problems like eutrophication, which is generally raise due to agricultural and sewage wastes. The other possibility is that since there are no major industries in the project area, the major source of organic pollutants is only the domestic source. Population density spread over sparsely located villages like Dasanapura and Harle certainly contributes towards total and fecal coliforms as excreta of the villagers due to lack of toilets in their houses. Thus present study concludes that river water was not polluted; all results are within permissible limit when compared with Bureau of Indian Standards (BIS) and National River water quality standards. INTRODUCTIONRivers are vital and vulnerable freshwater systems that are critical for the sustenance of all life. However, the declining quality of the water in these systems threatens their sustainability and is therefore a cause for concern. Rivers are waterways of strategic importance across the world, providing main water resources for domestic, industrial, and agricultural purposes (Faith, 2006).

Groundwater is almost globally important for human consumption as well as for the support of habitat and for maintaining the quality of base flow to rivers, while its quality assessment is essential to ensure sustainable safe use of the resources for drinking, agricultural, and industrial purposes. In the current study, 28 groundwater samples were collected around Vrishabhavathi valley region of Bangalore South Taluk to assess water quality and investigate hydrochemical nature by analyzing the major cations (Ca(2+), Mg(2+), Na(+), K(+)) and anions,(HCO(3)(-) Cl( - ), F( - ), SO(4)(2-), NO(3)(-), PO(4)(3),CO(3)(2-)) besides some physical and chemical parameters (pH, electrical conductivity, alkalinity, and total hardness). Also, geographic information system-based groundwater quality mapping in the form of visually communicating contour maps was developed to delineate spatial variation in physico-chemical characteristics of groundwater samples. Piper trilinear diagram was constructed to identify groundwater groups (hydrochemical facies) using major anionic and cationic concentration and it was found that majority of the samples belongs to Ca(2+)-Mg(2+)-Cl(-)-SO(4)(2+) and Ca(2+)-Mg(2+)-HCO(3)(-) hydrochemical facies. Wilcox classification and US Salinity Laboratory hazard diagram suggests that 92.86% of the samples were falling under good to permissible category and C3-S1 groups, respectively, indicating high salinity/low sodium.

Anekal Taluk lies in the southern part of the of Bangalore urban district, known for Bannerghatta wildlife sanctuary, Jigani industrial estate, silk industry, and the electronics city, the pride of India and hub of Bangalore's information technology. In the present study, evaluation of geochemistry of 28 representative bore wells samples from Anekal Taluk was undertaken. It was found that most of the samples (92.9%) belong to Ca(2+ )-Mg(2+ )-Cl( - ) -SO²⁻₄water type with Ca-Mg-Cl and Ca-Cl hydrochemical facies. The groundwater sources were further categorized as normal chloride (32.14%) and normal sulfate (100%) water types based on Cl and SO(4) concentrations. Majority of the samples (64.3%) belong to C3-S1 water class, indicating water with high salinity and low sodium. Positive index of base exchange indicates the chloro-alkaline equilibrium in the study area. Groundwater potential zonation map for Anekal Taluk was generated using multiparametric and weighted overlay method using the spatial analyst tool in ArcGIS v9.2. Accordingly, five distinct classes corresponding to good(high), moderate (medium), moderate to poor (low), poor (very low), and poor to nil (very low) groundwater potential zones were identified in the region. Of this, 85.27% of the study area belongs to good/high to moderate/medium groundwater potential and only 14.73% belonging to moderate/poor to nil groundwater potential zones.