Spatio-Temporal Dynamics of Fecal Bacterial Contamination in Groundwater and Associated Health Risks in the Feija Plain, Zagora, Morocco

Groundwater resources in arid agricultural regions face severe vulnerability to anthropogenic contamination, posing significant public health and environmental risks. This study evaluates the spatio-temporal dynamics of microbiological groundwater quality in the highly exploited Feija plain, Zagora province, Morocco. Over a 24-month period (2022–2024), eight strategic monitoring wells (P1–P8) were systematically analyzed for fecal indicators, general environmental flora, and strict pathogens. The results revealed a pronounced and recurrent seasonal cyclicity, with microbial loads systematically peaking during summer campaigns. For instance, Escherichia coli concentrations averaged 12.55 ± 2.91 CFU/100 mL in summer compared to 5.46 ± 2.39 CFU/100 mL in winter. Spatial profiling identified wells in the northern agricultural sector (P1–P3) as critical vulnerability hotspots, exhibiting maximum total coliforms reaching 1940 CFU/100 mL, whereas the hydrochemical reference site (P8) maintained baseline microbial signatures. Moreover, the consistent appearance of both recent ( E. coli ) and hardy ( Clostridium perfringens ) indicators from fecal pollution points to constant pollution in the area. Even though the average concentration of E. coli still lies within the acceptable level of irrigation according to the FAO (< 1000 CFU/100 mL), constant exceedances of strict WHO standards for zero tolerance in drinking water, together with occasional appearances of Salmonella spp., show deteriorated sanitary conditions in general. Highly correlated spatial variation of these indicators indicates that pollution of the aquifers is caused by diffuse agricultural pollution rather than any point source pollutants.