Analytic Evaluation of the Case Studies of Rivers and Reservoirs to Review Relative Impacts of Different Pollution Sources on Catchment Level Stream Ecosystems

The climatic variations, global warming, greenhouse gas emissions, non-regulated extraction of water from main sources/ground, increased use of fertilisers/slurry and ingress of chemicals with surface runoff all impact water quality/quantity. The pharmaceutical chemicals/antibiotics/drugs that are excreted by human beings and remain untreated in the treatment process are observed exceeding limits in the water bodies, causing further passive degradation of biodiversity and fatal intake by aqua life/animals and impacting the end users (human beings). This study has elucidated various case studies of rivers/ reservoirs to assess the pollution sources affecting the water quality on catchment level ecosystems. The study reviewed the case studies of ten rivers/reservoirs and wastewater treatment plants in developing/ developed countries and observed that the unregulated/unsafe adjacent land uses and untreated waste disposal in the streams are the main factors causing contamination in the water bodies. Untreated disposal of waste/sewage/effluents in the streams from domestic/commercial/agricultural fields is uncontrollably increasing, causing genetic variations, reduced abundance and depletion of growers and primary/ secondary consumers and affecting the health of the tertiary consumers in the ecosystems. The phenomenon is more pronounced for the drinking water reservoirs as they directly impact the health and well-being of the consumers, along with the increased cost of treatment of contaminated water. Catchment-sensitive farming and advanced filtration/treatment of water have been introduced as effective mechanisms to control this menace of pollution/contamination but are still not fully successful. The people’s awareness and public/private partnership in implementing the best/sustainable catchment level management strategies must be implemented to maintain the excellent quality of water from headwater to downstream