ABSTRACT
Almost all major rivers have been tapped at source for drinking water supplies. However, only 79% of the total demand for water of the urban population has been met.The rising demand for water in the valley has put pressure on the quality of both groundwater and surface water. In addition to the increasing demand on water, humans have impacted ecosystems directly through land-use change and the discharge of sewerage, and indirectly, by generating non-point source pollution that is introduced into streams and rivers via urban runoff (Voelz et al., 2005). Hence, there is a need to monitor these systems over long time periods to distinguish whether natural variability from anthropogenic stress is necessary for management (Resh and Rosenberg, 1989; Risser, 1991). Long-term data are necessary not only for detecting environmental trends, but also for putting the present situation into perspective (Magnuson, 1990).
