ABSTRACTKnowledge about the life cycle and survival mechanisms of leptospires in the environment is scarce, particularly regarding the environmental factors associated with their presence in ecosystems subject to livestock farming, where precipitation, seasonal floods, and river overflows could act as facilitators of leptospire dispersion. This study aimed to identify and study the presence ofLeptospiraspp. in the Lower Delta of the Paraná River and describe the physical, chemical, and hydrometeorological conditions associated with their presence in wetland ecosystems impaired by livestock raising intensification. Here, we show that the presence ofLeptospirawas determined mainly by water availability. We detected the speciesLeptospira kmetyi,L. mayottensis, andL. faineiand successfully cultured the saprophytic speciesL. meyerifrom bottom sediment, suggesting the association of leptospires with microbial communities of the sediment’s biofilm to enhance its survival and persistence in aquatic environments and adapt to changing environmental conditions. Knowledge ofLeptospirasp. diversity in wetlands and the impact of climate variability on the transmission of these organisms is crucial for predicting and preventing leptospirosis outbreaks in the context of human health.IMPORTANCEWetlands are environments that are often conducive to the survival and transmission ofLeptospirabecause they provide a suitable habitat for the bacteria and are often home to many animal species that can act as reservoirs for leptospirosis. Bringing humans and animals into closer contact with contaminated water and soil and increased frequency and intensity of extreme weather events may further exacerbate the risk of leptospirosis outbreaks, which is mostly relevant in the context of climate change and a widespread intensification of productive activities, particularly in the Lower Delta of the Paraná River. The detection of leptospiral species in wetland ecosystems impaired by livestock raising intensification can help to identify propitious environmental factors and potential sources of infection, develop preventive measures, and plan for appropriate responses to outbreaks, ultimately improving public health outcomes.