F. OCEANOGRAPHY. The causeway alternative would block wave and wind driven circulation on the eastern reefs and lagoon and modify tidal circulation between the ocean and lagoon. The addition of culverts and bridge openings through the causeway could reduce but not eliminate these effects. In the absence of an adequate Causeway maintenance and repair program, the failure of the causeway from storm wave damage could also disrupt water quality and circulation. Water quality effects from aquatic disposal of excavated soil could result in extensive turbidity and sediment plumes. The extent of these impacts can be reduced or eliminated by confined aquatic disposal in one of the lagoon bomb craters (such as BRAVO crater), land disposal on another island (such as Nam), or reef flat expansion of Bikini Island by disposal of excavated soil behind protective berms. Bagging of excavated soil prior to aquatic disposal would be another technique to reduce the effect of turbidity and sedimentation. Filling operations during causeway construction could also result in excessive production of turbidity and suspended sediments. Finally, cutterhead dredging operations to obtain sources of replacement soil could also generate excessive turbidity and sedimentaton; this can be reduced considerably by establishing settling basins on land to contain discharge slurry waters from the dredging operation. Quarrying operations on the reef flats to obtain armor rock and other stone for revetments should not result in major adverse effects on water quality, if done properly. G. MARINE BIOLOGY. Any alternatives involving construction in the water (such as for a causeway), aquatic disposal of soil, dredging, or other discharges could have an adverse effect on coral reef and subsistence fishery habitat. The causeway alternative in particular would be destructive to subsistence fishery and reef habitat from the direct effects of heavy equipment operation on the reefs and the discharge of fill materials and from the indirect effects of circulation and water quality changes as mentioned earlier. In addition, causeway construction and dredging could result in the outbreak of ciguatera fish poisoning which would further reduce the availability of fresh protein food resources to the islanders and increase public health risks. The latter effect could be mitigated by a monitoring program for the toxic algae and fish but most of the remaining adverse ecological effects would be unavoidable. The migrations of fish, shellfish, and other invertebrates between the lagoon and ocean side of the reef could also be inhibited by the causeway, but this effect can be reduced considerably by adequate numbers and sized culverts and bridge openings. Quarrying operations for protective structures including. the causeway revetment can also destroy existing marine biological habitat, but quarry sites and operations can be designed and located in a manner to reduce adverse effects and promote recruitment and colonization by fish and corals (based upon evidence from existing quarries at Kwajalein and Enewetak). S00014) E-14