The consumption of river water for agricultural purposes relies, among other aspects, on its microbiological quality, which is determined based on the concentration of thermotolerant coliforms it contains. The presence of antibiotic-resistant coliforms, despite not being a criterion considered by federal or state laws, is a serious concern. These bacteria cause difficult-to-treat illnesses and deaths if directly ingested by animals through water or if indirectly ingested through contaminated vegetables and grains. The present study evaluated the concentration of thermotolerant coliforms, and their resistance to ampicillin, ciprofloxacin, and tetracycline, in four rivers in rural areas of Santa Catarina, Brazil, that are used for animal consumption and crop irrigation. Analyses were carried out bimonthly for one year, between 2022 and 2023. Data were subjected to an analysis of variance and means were separated by the Tukey test. The average number of thermotolerant coliforms in all rivers was 709 ^. 100 mL^-1, which corresponds to Water Class 2 according to Brazilian legislation. Therefore, this water can be used for animal consumption and irrigation, in accordance with the way this water is used by the local population. However, 41% of coliform isolates were resistant to ampicillin, while 10% were resistant to tetracycline and ciprofloxacin. Resistant isolates were found in all rivers and on all sampling dates, which indicates the high frequency and abundant spread of these microorganisms. The presence of antibiotic-resistant bacteria in water can cause serious human and animal health problems if this water consumed without treatment. Considering the environment, the irrigation of vegetables and crops with resistant bacteria may also cause negative impacts on plant and soil microbial communities, leading to compromised ecosystem functions. We highlight the importance of monitoring the resistant bacteria in water, the need for environmental conservation programs, and the rational and correct use of antibiotics in order to minimize the occurrence of microbial resistance.