Urban streams receive excess nitrogen from numerous sources. We hypothesized that variations in carbon availability and subsurface infrastructure influence emissions of N₂O and other greenhouse gases (CH₄ and CO₂) as excess N is utilized by microbes. We sampled eight streams draining four categories of stormwater and sanitary infrastructure. Dissolved nitrogen concentration was the strongest predictor of CO₂ and N₂O concentrations, while C : N ratio was the strongest predictor of CH₄ in streams.