Long-residual herbicides can negatively impact aquatic ecosystems through surface runoff and leaching. This study evaluated the acute toxicity of indaziflam, sulfentrazone, clomazone, and tebuthiuron on Lemna minor and Azolla caroliniana. Experiments were conducted in the laboratory using a completely randomized design (CRD) with six concentrations of each herbicide across four replicates. The study assessed the concentration causing acute effects in 50% of the organisms (EC