Water quality assessment of the surface and groundwater from Wadi Al-Adairey, Hail, Saudi Arabia

Streams are valuable water resources for agriculture and human consumption. Herein, we conducted a field study to assess the quality of water by investigating the physicochemical and microbial properties of water samples derived from the Wadi Al-Adairey stream and the adjacent wells. We assessed a total of sixteen surface water and three groundwater samples in terms of various parameters, such as biological oxygen demand (BOD5), chemical oxygen demand (COD), dissolved oxygen, electroconductivity (EC), total dissolved solids (TDS), pH, temperature, minerals, heavy metals, and microbial concentration by monitoring total coliform bacteria. Except for COD and some minerals, all the investigated physicochemical parameters were satisfactory. A high total coliform count was found in the samples derived from the points close to the areas where the treated wastewater is discharged in the stream. However, the adjacent groundwater was free from coliforms. Overall, the groundwater showed good quality for all investigated parameters compared to the surface. A notable correlation was found between EC and TDS (r = 0.99), while correlations involving BOD, total coliform counts, and pH need to be confirmed by further studies. Moreover, some surface water samples showed high coliform counts even when derived from an area that is far from the discharging point of treated wastewater. This indicates the presence of another source of contamination that needs to be investigated. The findings from this work would allow us to establish an anticipated plan to preserve sustainable, safe water resources related to the Wadi Al-Adairey stream by implementing prevention plans and new policies.