Timing windows are the period(s) during the year when work may be carried out in and about water bodies with the lowest risk to fish and wildlife species and habitat. Timing windows and terms and conditions vary based on regional differences in fish and wildlife species and habitat, and geography. The timing window of least risk to fish and fish habitat must be applied to all activities in water bodies, as well as tributaries that have a risk of depositing sediment into water bodies. Windows of least risk are designed to protect all fish species known to occur in a water body.