River metabolism metrics reflect the production and consumption of carbon in an ecosystem, providing insight on river function and responses to environmental conditions. Continuous dissolved oxygen data enables these estimates of gross primary production (GPP) and ecosystem respiration (ER). In the Gallatin River, Montana, USA, nuisance algal blooms have occurred since 2017. We will assess why an initial metabolism metric is valuable for monitoring water quality in eutrophying rivers and will showcase a study design for doing so. The Gallatin blooms are hypothesized to occur in response to changing nutrient dynamics, likely due to development in the headwater tributaries. Historically, blooms also occur higher in the drainage, presumably due to naturally high levels of soluble reactive phosphorus (SRP). While the causes of the blooms are not fully understood, estimating metabolism will provide a foundation to assess the effects of nuisance blooms. State agencies and watershed management coalitions have been point sampling nutrients and measuring levels of dissolved oxygen since blooms began. However, dissolved oxygen measurements are not currently spatially distributed, and models of metabolism have not been fit to these data. Beginning oxygen data collection before spring runoff will record early deviations or spikes in gross primary production, which could signal the incipient establishment of a seasonal algal bloom. Ultimately, we will demonstrate how understanding the influence these blooms have on ecosystem productivity enables widespread and long-term monitoring of algal dynamics and the prediction of future blooms.