The impact of Pampa Irrigation Project canal on the water quality of dugwells adjacent to the Pampa river bank is studied for a period of two years. For many years, groundwater was thought to be protected from contamination by layers of rock and soil that has filters but contaminants do make their way into the groundwater and affect its quality. However, infiltration of water from adjacent rivers and canals affects the physicochemical attributes of ground water. Hence, there is need for concise assessment of the physical and chemical properties of water obtained and distributed from this source. Wastes generated by the thick population resident along the Pampa River banks make this river the most polluted one in Kerala and possibly in India as a whole. While action is being contemplated to reduce the waste disposal at Sabarimala and other locations connected with the pilgrimage, no action is being taken to verify and check the waste disposal from the river banks. The river water level rises abruptly with initiation of South West (SW) monsoon recharging the aquifer along the banks and possibly polluting the drinking water from dug wells. Maramon, one of two stations in studied is also under the influence of an irrigation canal that is opened without any specific time interval also causes contamination of dugwells along with the river born contaminants. Premonsoon and monsoon water samples from river and three dug wells in a transect is studied for its quality during 2014-15 period. Physico-chemical parameters such as pH, conductivity, TDS, nitrate nitrogen, total iron and phosphate and bacteriological parameters such as total coliforms, faecal coliforms and streptococci were analysed. In general, the monsoons had a clear influence on the dug water table in which SW monsoon increased the maximum level in most of the wells in the study area. Water table fluctuation in Maramon was visibly irregular possibly due to the influence of water that irrigated the area by Pampa Irrigation Project (PIP).pH broadly varied between 6.0 in well water at Maramon during SW monsoon 2014 and7.3 in river water at Thottappuzhasserry
without much spatialvariation. In general, both surface and ground water have conductivity below the recommended standards and higher conductivity noticed in river water may be due to stagnation of water due to sand mining. TDS varied from 21mg/l at dugwell two at Thottappuzhasery during Southwest monsoon 2014 to 51mg/l in river water at Maramon during premonsoon 2014. Nitrate nitrogen concentration ranged from 3.38mg/l at dugwell at Thottappuzhasery to 8.23mg/l in river water. Higher values observed in well waters of Maramon irrespective of season might have occurred due to infiltration of contaminated water from PIP canal. Values of total Iron varied from 0.08mg/l at dugwell two at Thottappuzhasery during SW monsoon 2014 to 0.84mg/l in river water at Maramon during premonsoon 2014. The increase in concentration of iron observed in some ground water stations during rainy season could be due to leaching of iron naturally present in lateritic soil facilitated by the unlined nature of wells. Phosphate concentration fluctuated between 0.04mg/l at dugwell one at Thottappuzhasery during pre-monsoon 2014 to 0.54mg/l in river water at Thottappuzhasery during south west monsoon 2015. Spatial and temporal variation was negligible except the high occurrence at well one at Maramon, a highly urbanised point under the influence of PIP canal.
