Water Quality At Mountain Springs Used For Drinking Water In The El Cercado Area, Dominican Republic

Abstract

Globally, many hundreds of millions of people living in developing rural mountainous areas are believed to lack access to a safely managed drinking water source. Typically, this population subset is sustained by groundwater emerging at mountain springs, which previous studies in three different world regions have found to be commonly contaminated with E. coli. The presented research focuses on water quality of mountain springs in a rural area of western Dominican Republic. Initial preliminary investigations established understanding of study-area-wide topography and geography. Thirty-seven mountain springs throughout the study area were assessed qualitatively (for land use, geology, infrastructure, and biota) and quantitatively (for pH, temperature, electrical conductance [EC], total dissolved solids [TDS], nitrate, alkalinity, and E. coli) at 109 sampling points during three field research trips in 2017 and 2018. The study area is comprised of a high percentage of developed and agropastoral land. The mountains which surround the study area are underlain by highly fractured carbonate rock. A majority of springs were located near or in a river/streambed and had up-slope agropastoral land. Generally, a decrease in elevation of mountain springs was related to a decrease in water pH, and an increase in temperature, EC, TDS, and alkalinity for springs in the same general mountain area. E. coli concentrations of emerging groundwater were compared to water collected from the likely points of user collection (LPUC; e.g., spring box, spring pool, pipes) and results show that a higher percentage of LPUC samples were considered Unsafe, while a higher percentage of groundwater upwelling samples were considered Low Risk/Safe: 35% for upwelling and 40% for LPUCs. Water at springs was commonly contaminated with Intermediate to Unsafe levels of E. coli: >70% and >65% of springs sampled at the upwelling and spring box, respectively. E. coli was present even at springs “protected�? by spring boxes, indicating that this infrastructure does not prevent contamination of spring water. Recommended future work includes using relatively low-cost, portable rock-coring machines to drill wells at mountain springs for studying the extent of bacterial and nitrate contamination by accessing safe groundwater tens of meters below ground for community water supply.