ENVIRONMENTAL EFFECTS

The selected plan would cause a temporary increase in suspended solids levels in the river in the vicinity of the dredge operation. However, this increase would be near the river bottom and would not be as high as that expected to be caused by natural storm events. Any benthic communities occurring in the area to be dredged would be impacted during construction and in each subsequent maintenance dredging cycle. The proposed deepening would result in an increase in salinities both up and downstream of U.S. Highway 17. The maximum increase above U.S. Highway 17 would be from 0-0.68 ppt, and below U.S. Highway 17 the maximum increase in salinity would be 0-2.03 ppt. This increase is not expected to significantly impact organisms inhabiting this area or using the area as a feeding or spawning area.

CONSTRUCTION CONSTRAINTS DUE TO ENVIRONMENTAL REQUIREMENTS

The U.S. National Marine Fisheries Service and the U.S. Fish and Wildlife Service had stipulated construction requirements for protection of endangered species. The Georgia and South Carolina Water Quality Certifications also include constraints for protection of water quality. The following is a summary of these construction constraints, which are presented in more detail earlier in this report.

The Savannah District will ensure that construction procedures will adhere to these requirements. The impacts of these requirements on project costs have been considered during the development of cost estimates.

Constraints for Any Dredging Equipment

(1) The contractor will be required to instruct all personnel associated with the dredging of the presence of manatees and the need to avoid collisions with the manatees.

(2) All personnel associated with the dredging will be advised that there are civil and criminal penalties for harming, harassing, or killing manatees which are protected under the Endangered Species Act of 1973 and the Marine Mammal Protection Act of 1972.

(3) Any collision with a manatee will be immediately reported to the manatee "hotline" (1-800-342-1821) and the U.S. Fish and Wildlife Service, Brunswick Office at (912) 265-9336.

(4) The contractor will be required to keep a log detailing sightings, collisions, or injury to manatees which occur during the dredging operation.

(5) A report summarizing the above incidents will be provided to the U.S. Fish and Wildlife Service, Brunswick Office. (6) All vessels associated with the project will operate at "no-wake" speeds at all times while in the water where the draft of the vessel provides less than three feet of clearance from the bottom and that vessels will follow routes of deep water to the extent possible.

(7) The contractor will be required to instruct all personnel associated with the dredging of the presence of Right Whales and the need to avoid collisions with these mammals. The contractor will also be required to brief all personnel on the habits and behavior of the Right Whale.

(8) During the months of December to March of each year the contractor will be required to restrict dredge and attendant vessel speeds to less than 5 knots during night operations unless daily aerial surveys of the area reveals their are no whales within 15 miles of the project area.

(9) The contractor will be required to post a whale watch and submit a whale watch plan prior to conducting any dredging activities at the site.

(10) All work performed during construction will be done in a manner So as not to violate applicable water quality standards.

(11) No oils, grease, materials or other pollutants will be discharged from the conducted activities which reach public waters.

(12) No dredging will be conducted during the striped bass spawning period from March 16 to May 31 of each year above river mile 5.0.

(13) Water quality monitoring must be conducted in accordance with the plans which have been approved by the Georgia Department of Natural Resources. The plans include provisions for suspension of dredging during any periods when D.O. values drop below 3.0 mg/l.

(14) Prior to or concurrent with dredging of the Savannah Harbor, New Cut Channel must be filled and the Back River tide gates removed from operation. (This has been completed under the Section 1135 Project Modification). (15) Best Management Practices to control erosion during and following construction of dikes across New Cut Channel and the removal of the tide gates from operation must be implemented. (This has been completed).

(16) All effluent from Disposal Area 12 must be discharged to the Back River and none to the Wright River or its tributaries. Diversion of all maintenance dredging effluent from Disposal Area 12 to the Savannah Harbor side must be studied and the best means to divert all effluent from Wright River determined. The Savannah District must submit a time schedule for relocation of the weir structures at Disposal Area 12 to the South Carolina Department of Health and Environmental Control prior to dredging of the Savannah Harbor. (All weirs from area 12 have been moved to the Savannah Harbor side).

(17) Dredging of Savannah Harbor must be limited, if possible, to the winter months (November 1 through March 1). (18) Dredging shall be conducted in compliance with the Programmatic Memorandum of Agreement on cultural

resources.

Additional Constraints for Hopper Dredges

(1) All hopper dredging activities shall be completed during the months of December through March when sea turtle abundance is believed to be at its lowest.

(2) Trawl surveys shall be conducted prior to hopper dredging to ensure a low abundance of sea turtles. These surveys shall consist of a minimum of 50 trawls of 30 minute duration within 5 days. The trawler will be fitted with two 60-foot flat style trawling nets consisting of 8 inch mesh. The nets will be fitted with mud rollers, floats, and a tickler chain. All turtles caught will be identified, measured, and tagged prior to being relocated a suitable distance from the ship channel. Blood samples will be taken from captured sea turtles and analyzed for standard parameters developed by the Corps of Engineers Waterways Experiment Station.

(3) The Savannah District shall arrange for National Marine Fisheries Service approved observers aboard hopper dredges to monitor the hopper spoil, overflow and inflow screening, and dragheads for sea turtles and their remains. Observers shall be aboard the dredges 100 percent of the time. Weekly summary reports will be submitted to the National Marine Fisheries Service, Southeast Regional Office, by the observers to assess the monitoring effectiveness and sea turtle takes. During all hopper dredging operations, observers should maintain a watch for Right Whales during dredge transit to and from the disposal site.

(4) The hopper dredge shall be equipped with screening or baskets to better monitor the intake and overflow of the dredged materials for sea turtles and their remains. The baskets or screening devices shall have openings of approximately 4 inches by 4 inches and shall provide 100 percent coverage of the hopper inflow. These screens should sample at least 70 percent of the overflow area and should be installed at the applicable area, such as the "skimmer funnels" and the starboard and port sides of the vessels. Every effort possible should be made to effectively sample the turtle parts which travel through the hopper and exit in the overflow material.

(5) The hopper dredge will be equipped with California type dragheads or other equally acceptable draghead concurred in by the National Marine Fisheries Service.

(6) Hopper dredge dragheads will include a turtle deflector device approved for testing by the National Marine Fisheries Service.

(7) Dredging must be suspended for reinitiation of consultation with the National Marine Fisheries Service upon the taking of two Kemp's ridleys; three greens, hawksbills, or leatherbacks; five loggerheads; or any combination of the above species that equals five.

(8) A preliminary report summarizing the results of the dredging and the sea turtle take must be submitted to the Savannah District and the National Marine Fisheries Service within 15 working days of completion of any given dredging project.