Nested subcatchments often exhibit diverse geology, land cover, topography, and hydrology and may contribute disproportionately to the carbon (C) and nutrient exports observed at the watershed outlet. However, how subcatchment carbon and nutrient contributions change as the river network expands and contracts is unknown in the Coastal Plain landscape. We addressed this gap by intensively sampling spatially-distributed water chemistry in 20 nested subcatchments across the forested South Sandy watershed (~125 km2) in the Coastal Plain landscape of Alabama, USA. We use these monthly watershed-wide sampling campaigns to assess the spatial scale and persistence of C, [N]itrogen and [P]hosphorus fluxes. We found that small subcatchments (4-14 km2) strongly influenced C, N, and P exports, highlighting an array of localized sourcing and processing in dynamic headwaters. Additionally, we found that C was exported conservatively, while N (as nitrate, NO3-) and P (as phosphate, PO43-) were generally produced across the watershed. Also, N concentrations were more stable than C and P during the sampling period (r2 > 0.50), indicating that sampling the exact locations may result in a similarly spatial distribution of nitrate concentration within the South Sandy watershed. Understanding solute export in the South Sandy watershed is crucial for identifying subcatchments representing watershed-scale behavior. These subcatchments can serve as key references for more effective scaling of biogeochemical dynamics in Coastal Plain rivers.