Tidegate and Floodgate Maintenance Species Impact Analysis. The potential effects to fish from tidegate and floodgate maintenance increases with the degree to which the watercourse or shoreline is disturbed, and the degree to which motorized equipment is used to complete the maintenance. Minor repairs have a very low potential to impact fish, whereas major repairs or replacement tend to have increasingly greater potential to impact fish. The potential for fish to be impacted by tidegate and floodgate maintenance is also related to the size of fish. Larger fish are stronger swimmers and therefore better able to escape and avoid the potential impacts of maintenance activities, whereas smaller fish are weaker swimmers and therefore at greater risk of being killed or injured. The potential for fish to be impacted is greater in those habitats where small fish rear and seek refuge. The habitats typically associated with tidegates and floodgates in the Skagit delta and estuary provide optimal rearing and refuge habitat for smaller fish, whereas larger fish tend to seek optimal rearing and refuge conditions in deeper water and offshore habitats. The potential for fish to be impacted is also dependent upon small fish being present at the tidegate or floodgate sites. For many fish species, dependence on delta and estuary habitats is seasonal. The time of the year when juvenile fish utilize the delta and estuary habitats for rearing and refuge is different for different fish species and life histories. For salmonid species, small juveniles typically depend on the Skagit delta and estuary habitats between February 1 and July 31 during which time they are at greatest risk of being impacted by tidegate and floodgate maintenance. Tidegate and floodgate maintenance activities can result in direct and indirect impacts to fish. Direct impacts include physical and/or chemical trauma to the fish that can result in injury or death. Indirect impacts are temporary and do not directly kill or injure the fish. Indirect maintenance impacts disturb and/or alter the watercourse and shoreline habitats upon which fish depend for rearing and refuge thus compromising their rearing ability and their potential to survive. The following maintenance conditions could result in direct fish impacts: Whenever a watercourse is excavated with motorized equipment, fish can be killed or injured. Fish can be physically removed from the watercourse in the bucket of the excavator and discarded on the shoreline. The excavator bucket can also physically injure ...
