Fast urbanization can result in significant stormwater runoff pollution due to changes in land use. A 3-year study on the distribution and temporal variations of urban water pollutants in stormwater runoff was conducted, with a specific focus on the influence of land-use patterns in the recharge zone of a regional karst aquifer in Texas (Edwards Aquifer). The presence and concentration of various water pollutants including total suspended solids (TSS), total dissolved solids (TDS), nutrients (nitrite, nitrate, ammonia and phosphate), total carbon (TC) and total organic carbon (TOC), oil and grease (O&G), and eight heavy metals (Fe, Mg, Cu, Pb, Zn, Ni, Cr, Cd) were measured in stormwater samples collected from three bioswales. Results show that average TSS in site S1 (598.87 mg/L) and S2 (628.69 mg/L), COD in site S1 (103.97 mg/L), phosphate in sites S1 (1.44 mg/L) and S3 (0.65 mg/L), and O&G (ranging from 50.63 to 84.32 mg/L) in all three sites surpassed the national average (NSQD). While residential areas were identified as the main sources of nutrients, roads and parking lots were associated with heavy metals. Temporal variations indicated the effect of antecedent dry days on the concentrations of TSS and phosphate. Growing seasons as well as pet feces were associated with elevated nitrate concentrations in residential areas. Organic carbon was found overall higher during warmer months, while heavy metals during cooler months. The study also identified specific land-use practices that can be enhanced to mitigate stormwater pollution, such as the implementation of permeable pavements, rain gardens, and stricter waste disposal regulations. The results of this study offer valuable insights for enhancing stormwater management strategies to better mitigate stormwater pollution in urban regions.
