Assessment of spring water quality in Jhimruk River Watershed, Lesser Himalaya, Nepal

Springs are primary water sources for drinking and sanitation in rural households of mountainous areas and are ecologically important as they provide habitat to diverse macroinvertebrate assemblages. This study assesses the spring sources to clarify concerns about the quality and safety of this water used for human use, as well as the condition of the biological habitat in the Jhimruk River Watershed (JRW), Nepal. Spring sources were mapped and samples of water and benthic macroinvertebrates were analyzed during the pre- and post-monsoon seasons. One hundred and two springs were documented with their characteristics. Field assessment shows that the discharges of more than 90% of the springs have decreased in the last 10 years which has increased the water stress for drinking water sources and for sanitation for communities in the region. Except for pH, EC, and total hardness, all other measured physicochemical parameters were below the WHO and National Drinking Water Quality Standards of Nepal, currently indicating no threat to consumer's health. Water quality index scores indicate the water from the springs is excellent in the post-monsoon and excellent to good in the pre-monsoon seasons. Low seasonal chemical variability observed with a higher spatial difference, driven by the geology. We documented 38 macroinvertebrates families in the post-monsoon and 32 families in the pre-monsoon season. Macroinvertebrate richness [total and Ephemeroptera-Plecoptera-Trichoptera (EPT)] was greater in flowing springs compared to stagnant springs which were numerically dominated by Chironomidae. Discharge rate, elevation, EC, and nitrate concentrations were the main influencing factors shaping macroinvertebrate assemblages in the springs. We emphasize that actions must be implemented to conserve the societal and ecological value of Himalayan springs.