While maintaining the capacity of the channels for efficient movement of navigation, the action will remove or disturb motile and bottom dwelling organisms, cover vegetation of value to fish and other wildlife, result in temporary increases in turbidity from dredging and disposal operations, possibly resuspend some polluted materials, displace fish life during operations, and continue existing low productivity levels in channel and disposal areas. Objectionable odors may result from disposal of dredged material on emergent areas. Productive marsh habitat will be converted to high ground habitat in some disposal areas. Continued maintenance will preserve environmental benefits such as improved water circulation and disposal islands that resulted from channel construction. Other benefits include continued access to back bays for recreational craft, bird nesting areas on disposal islands, oyster development on submerged dispoasal areas, and fish escape routes, migration routes, and refuge areas. Maintenance is essential to the existing economy and will contribute to continued economic growth of the Texas Gulf Coast.