Intensifying wildfire regimes in many parts of the world are increasing the production of pyrogenic organic matter (PyOM), with potential implications for water supplies that are critical for domestic, industrial, agricultural, and ecological needs. This study provides a novel assessment of the influence of PyOM on aquatic ecosystems and showed that PyOM can be actively transformed in aquatic ecosystems and may be an increasing source of C emissions to the atmosphere as the prevalence of wildfires increases.