The suspended sediment (SS) load is a key indicator of soil erosion and is best understood through extensive monitoring of both streamflow (Q) and SS concentrations (SSC) under varied hydrological conditions. This study aimed to quantify SS loads in two mountain river basins in Southeast Italy: the Carapelle (506 km2) and the Celone (72 km2) in Apulia, using different monitoring approaches (continuous and discrete). Specifically, the study sought to develop sediment rating curves to address SSC data gaps. Sediment rating curves were developed for three hydrological conditions—high, normal, and low flow—to estimate SSC for days with missing data. The results showed that the annual specific sediment load ranged between 2.4 and 6.06 t ha−1yr−1 for the Celone river and from 0.9 to 7.45 t ha−1yr−1 for the Carapelle river. High-flow periods contributed to over 80% of the total SS load, while low-flow periods accounted for less than 1%. This study underscores the critical role of hydrological regimes in sediment transport within Mediterranean river basins and demonstrates that sampling duration and characteristics are essential factors for accurately estimating sediment loads.