. The

In order to assess the surface water quality a total of forty two surface water samples were collected in pre-monsoon and post-monsoon seasons of 2008, 2009, 2010 and were analyzed for electrical conductivity, pH, total dissolved solid, Na, K, Ca, Mg, HCO 3 , Cl, and SO 4 . The chemical classification of surface water has been studied using L-L diagram, given by Langelier and Ludwig (1942)1, surface water of both the seasons belongs to sodium Cl+SO4 type. The results show that surface water is affected by industrial effluents which have high concentration of BOD, COD, Na, Ca, Mg, K, Cl, SO4 and HCO3. However the three years of study shows that the surface water pollution in Bolaram and patancheru industrial development areas has significantly reduced, due to fact that the emission of effluents are treated regularly for the last few years.

the present study area there are about 400 (large and small) industries, and since 1977 these have been engaged in the manufacture, production, and processing of pharmaceuticals, paints and pigments, metal treatment and steel rolling, cotton and synthetic yarn, and engineering products.Most of them use various inorganic and organic chemicals as raw materials.These industries discharging their waste effluents directly into the streams.

The Study Area
The Patancheru and Bolaram Industrial Development Areas (IDA) (78°08'-78°23' east longitude and 17°30'-17°42' north latitude) of the Medak district are located about 35 km from Hyderabad, Andhra Pradesh (A.P.), India; the location is shown in Fig. 1.The study area form the part of the Nakkavagu watershed.

Nakka vagu
The Pamulavagu, Peddavagu and Nakkavagu streams, while carrying industrial effluents also acts as diffuse sources of contamination along their courses to the confluence with the Manjira River.Apart from this, streams tanks both of medium and small size form the other surface water bodies of patancheru and bolaram industrial areas.

METHODOLOGY Hydrochemical sampling procedure
The objective of sampling is to collect a portion of material small enough in volume to be transported conveniently and handled in the laboratory while still accurately representing the material being sampled (APHA, 1992) 3 .Samples, however, have to be handled in such a way that no significant change in composition occurs before the tests are made.
A total number of 42 surface water samples were collected for physico-chemical analysis in two successive pre-and post-monsoon seasons of 2008, 2009, 2010.
The water samples were collected and stored in 1 liter capacity clean plastic bottles.Before collection of samples, the bottles were properly washed.Prior to collecting the samples, the containers were rinsed by the water to be sampled.The major ion analyses were carried out at National Geophysical Research Institute, (NGRI) Hyderabad.

Analytical techniques for major ions
The water samples were analyzed as per the standard methods of APHA (1992).Values of pH were measured by a portable digital water analyses kit with electrodes.The instrument was calibrated with buffer solutions having pH values of 4 and 9. Total dissolved solids (TDS) were calculated by summing up the concentrations of all the major cations and anions.The values of electrical conductivity (EC) were measured by portable kit with electrodes.The concentrations of Ca ++ , Mg ++ , Cl -, HCO 3 -and total hardness were determined by volumetric method.Ca ++ and Mg ++ were determined by EDTA titration.For HCO 3 -, HCl titration to a methyl orange point was used.Chloride was determined by titration with AgNO 3 solution.Flame emission photometry has been used for the determination of Na + and K + .In this method water sample is atomized and sprayed into a burner.The intensity of the light emitted by a particular spectral line is measured with the help of a photoelectric cell and a galvanometer.Sulphate was determined by gravimetric method.

RESULTS AND DISCUSSION
The analytical data of successive pre-and post-monsoon seasons for surface water sample corresponding to June 2008 and November 2008, June 2009 and November 2009 June 2010 and November 2010 are given in table 1, 2, 3,4,5,6.

Classification of surface water
The chemical classification of surface water has been studied using L-L diagram, given by Langelier and Ludwig (1942) 4 for both, premonsoon and post-monsoon of 2008 seasons.Surface water samples have been plotted to discern any conspicuous changes in the overall chemical behavior of surface water during the two major seasons of the year.Both the plot belongs to pre and post-monsoons of 2008 indicate there are no major changes in the chemistry of surface water samples.Surface water of both the seasons belongs to sodium Cl+SO 4 type.

Physico-chemical attributes of surface water
The properties of surface water of the area under study, in terms of fundamental parameters, such as, pH, total dissolved solids, Electric Conductivity, COD and BOD are given below.

Hydrogen Ion Concentration (pH)
The pH values were measured at well sites, are lies in the range of 7.25 to 8.41 and 7.35 to 8.0 during pre-monsoon 2008 and post-monsoon 2008, respectively .The surface water thus is mildly acidic to slightly alkaline in nature.

Electrical Conductivity
Seasonal variations showed higher value of EC in pre-monsoon 2008 and lower value in post-monsoon due to dilution with rain water.The values obtained were very much higher than the permissible limits.The conductivity was recorded in different seasons from minimum of 17 mS Cm -1 to a maximum of 33 mS Cm -1 in pre-monsoon 2008 season and from minimum of 14.9 mS Cm -1 to a maximum of 29.3 mS Cm -1 in post-monsoon 2008 season..

Total Dissolved Solids (TDS)
In water, total dissolved solids are composed mainly of carbonates, bicarbonates, chlorides, phosphates and nitrates of calcium, magnesium, sodium, potassium and manganese, organic matter, salt and other particles 5 .At high flows, the TDS values tend to be diluted by surface runoff and for most rivers there are an inverse correlation between discharge rate and TDS 6 .As expected, the maximum total dissolved solids were observed during the pre-monsoon season of 2008 (21600 mg/l) than the post-monsoon (18900 mg/l), this is due to dilution factor during the rainy season.Higher level of TDS during pre-monsoon season is more likely due to the influence of industrial activities such as effluent addition to the surface water.Waters with high total dissolved solids (TDS) are unpalatable and potentially unhealthy.

COD and BOD
COD pointing to a deterioration of the water quality caused by the discharge of industrial effluents 7 .The COD in the surface water ranges from 3100-27000 mg/l in pre-monsoon 2008 and from 1450-14500 mg/l in post monsoon 2008.High BOD level indicates decline in DO, because the oxygen that is available in the water is being consumed by the bacteria leading to the inability of fish and other aquatic organism to survive in the river 8 .The BOD in the surface water ranges from 2400-20200 mg/l in pre-monsoon 2008 and from 660-12500 mg/l in post monsoon 2008.

Temporal variation trends of major ions in surface water
Data of concentration of major ions of preand post-monsoon 2008, pre-and post-monsoon 2009, and pre-and post-monsoon 2010 are given in Table .The concentration values of all the samples are discussed in detail.Chloride, in corresponding sampling periods, ranges from 5593 to 11214 mg/l, 4300 to 8734 mg/l, 3100 to 6560 mg/l and 4903 to 9900 mg/l, 2899 to 7021 mg/l, 2401 to 5720 mg/l respectively.

CONCLUSIONS
Surface water has the highest concentration of cations and anions.Surface water is affected by industrial effluents which have high concentration of Na, Ca, Mg, K, Cl, SO 4 and HCO 3.These parameters are in more than desirable limits which could be the result of direct dumping of effluents into the water bodies.The industrial effluents are let into the stream directly during rainy days thus leading to accumulation of elements in surface water, which together with rain water, flow down to Nakkavagu stream and join the major drainage system and these water in due course percolate down to join ground water reservoir.The effect of industrial pollution thus can be seen along Nakkavagu and its adjourning areas.
The three years of study shows that the surface water pollution in Bolaram and patancheru industrial development areas has significantly reduced, due to fact that the emission of effluents are treated regularly for the last few years.The low reduction in surface water pollution may be due to rainfall dilution.

Table 1 :Table 5 :Table 6 :
Physico-chemical characterization of surface water of pre-monsoon 2008 IN mg//cm all other parameters in mg/L Except pH Table 2:Physico-chemical characterization of surface water of post-monsoon 2008 IN mg/Physico-chemical characterization of surface water of pre-monsoon 2010 in mg/Physico-chemical characterization of surface water of post-monsoon 2010 in mg/parameters are graphically represented as