Can bleach be used to clean the interior of a horse stable that was flooded with river water?

Bleach can be used, but there are more effective disinfectants for a stable. To disinfect the stalls or paddock, organic matter needs to be removed. The bedding needs to be removed, and the walls and fencing need to be swept or scrubbed off. A pressure washer should then be used with a strong detergent to wash all surfaces. Some areas that are heavily stained may require hand scrubbing. After all surfaces are cleaned and rinsed, as much water or moisture should be removed as possible before the disinfection process is begun. Phenolic compounds can be used in a sprayer and sprayed on all surfaces, including the floor, and allowed to dry. Do not rinse. In an outbreak of an infectious disease, repeat the spraying and drying of the disinfectant.
Buckets and any portable feeding or drinking vessels should be scrubbed, disinfected, and rinsed. Anything from which the horse will eat or drink should be rinsed of the disinfectant once it has dried.
Note: As with any use of chemicals, it is important to read the label for suggested use in and around animal confinement areas. Some will restrict use around feeding and watering areas; in any case, it is recommended to move animals away from areas being disinfected as a precaution to avoid any chance of skin or eye irritation during the cleaning process.