Primary production can contribute to nitrate uptake in streams through the stoichiometric coupling of the diel C and N cycles. While others have observed the effect of autotrophic uptake on the nitrate cycle, it has not been quantified on large spatial scales. Here we asked, what fraction of the total nitrate uptake is from autotrophs? We use high-frequency, long-term National Ecological Observation Network [NEON] sensor data from 20 sites to inform a mathematical model that estimates 1) the sunlight-driven autotrophic uptake of nitrate and 2) the equilibrium turnover of nitrate from other processes. While NEON data makes this study possible, it also has limitations: there is only one SUNA nitrate sensor per site. This necessitates a one-station nitrate model to compare nitrate and oxygen, which may be difficult because the two compounds have different turnover lengths. Thus our second question is, how effectively can our single station model capture the interactions between nitrate and oxygen at NEON streams? Estimates of nitrate uptake from from LINX II [the NO3- focused Lotic Intersite Nitrogen eXperiment] indicate that autotrophic nitrate uptake constitutes ~ 30% of total stoichiometric demand for N, based on C:N ratios found in periphyton. Our models found that autotrophic uptake is closer to 7% of total nitrate uptake calculated from high-frequency sensor output. Our single-station model does effectively capture autotrophic uptake, because the effective reach length (velocity/turnover rate) in our streams is shorter than major discontinuities in the stream network; this indicates that nitrate ‘resets’ itself within the effective reach, just like oxygen, thus making single-station models feasible.