The National Rivers Water Quality Network (NRWQN) has never included suspended particulate matter analyses in all 26years of its existence, although optical proxies (visual clarity; turbidity) are measured routinely. The purpose of this add-on to the NRWQN was to 'calibrate' those optical proxies to total suspended sediment (TSS) in particular rivers - to confirm the original supposition in design of the NRWQN that routine, ongoing measurement of TSS would be too expensive and not sustainable when most visits to sites intercept rivers in baseflow when TSS is relatively low and sediment flux very low. The opportunity was taken during this add-on also to measure organic content of SPM in rivers (as volatile suspended sediment; VSS) and the nutrient (N and C content) of this organic matter (particulate organic carbon, POC; particulate organic nitrogen, PON). The TSS data in the dataset has already been published (along with correlating NRWQN data) by Davies-Colley et al. (2014) and Ballantine et al. (2014). [Ballantine, D.J.; Hughes,A.O.; Davies-Colley,R.J.(2014).Mutual relationships of suspended sediment, turbidity and visual clarity in New Zealand rivers. Sediment Dynamics from the Summit to the Sea Proceedings of a symposium held in New Orleans, Louisiana, USA,11–14 December 2014)(IAHS Publ. 367, 2014). doi:10.5194/piahs-367-265-2015 Davies-Colley, R.J.; Ballantine, D.J.; Elliott, S.H.; Swales, A.; Hughes, A.O.; Gall, M.P. (2014).Light attenuation - a more effective basis for the management of fine suspended sediment than mass concentration? Water Science and Technology 69(9):1867-74. doi: 10.2166/wst.2014.096.]