Glyphosate, the active ingredient in herbicides like RoundUp, is often used in commercial agriculture as well as in residential gardens. Glyphosate exposure can lead to neurological system failure in invertebrates and fish, and can cause oxidative stress in aquatic plants, animals, and microorganisms like cyanobacteria and certain fish pathogens. Despite its widespread use in the Eastern Washington region, its persistence and movement through the environment remains unclear. Here, we present findings from a nascent long-term water monitoring initiative that reveal seasonal changes in Glyphosate concentrations in two key tributaries of the Spokane river: Hangman (Latah) Creek (HC), and the Little Spokane River (LSR). Water samples collected by citizen scientists between October 2024 and into April 2026, were analyzed using a commercially available ELISA kit. Overall, glyphosate levels at both sites were significantly lower than the EPA Maximum Contaminant Level Goal (MCLG) of 700 µg · L-1, and were often below the detection limit of the immunoassay kit used. Glyphosate levels ranged from 0 to 0.12 µg · L-1 (mean: 0.01 ± 0.03 µg · L-1) in the LSR, and from 0 to 0.74 µg · L-1 (mean: 0.07 ± 0.15 µg · L-1) in HC. Seasonal fluctuations revealed spikes in February and June 2025 - consistent with the timing of agricultural applications, and suggesting a clear mode of entry for glyphosate into the local watershed. Our ongoing research also suggests that even at these low concentrations, Glyphosate has the potential to influence HAB-forming cyanobacteria and fish pathogens.