The environmental impacts address- 

 ed in the negative declaration were 

 mostly localized in nature. They did, 

 however, emphasize the role of habitat. 

 Features of the project related to ter- 

 restrial and aquatic ecological impacts 

 that were addressed include 



o No unique vegetation will be re- 

 moved. 



o Some submerged land will be filled. 



o Revegetation will be considered. 



o Net impact of filling kept at a min- 

 imum by increasing bridge length 

 and utilizing steep side slopes on 

 approaches. 



o Control of turbidity due to con- 

 struction will be studied. 



o Borrow from dry land will be pre- 

 ferred as compared to borrow from 

 submerged lands and from the pre- 

 viously disturbed areas as compar- 

 ed to new areas. 



o Offshore dredging for fill in vicin- 

 ity of bridges not anticipated ex- 

 cept where construction dredging 

 may be required. 



o If submerged borrow operations 

 were undertaken, containment of 

 the "dredge plume" would be an 

 important concern. 



o If dredging of marinas from the 

 onshore areas is done, no connec- 

 tion should be opened until turbid- 

 ity has dropped to safe levels. 



o Holding borrow site depth to ap- 

 proximately 20 to 25 ft will be con- 

 sidered. 



o Width of the fill will be minimized 

 by using steep slopes. 



o Structural retaining systems will 

 be considered in some locations to 

 reduce the area of bottom filled. 

 Sheet pile walls or tie-back types 

 will probably not be used due to 

 potential washout. 



o Air quality standards will not be 

 violated. 



o Where FHWA exterior noise criteria 

 are expected to be exceeded, ex- 

 ceptions will be requested. 



o It is improbable the runoff from 

 bridge or road surfaces would vio- 

 late State water quality standards. 



o The possibility of spillage of toxic 

 materials from trucks will be re- 

 duced because the road will be 

 safer. 



o Construction and maintenance of 

 new bridges will be according to 

 State Standard Specifications for 

 "Prevention, Control and Abate- 

 ment of Erosion and Water Pollu- 

 tion." 



o The use of sediment traps during 

 construction will be considered. 



o Interim use of webbing, matting, 

 mulching, and other mechanical 

 means of erosion control will be 

 provided for. 



o Consideration will be given to 

 special specifications for bridge 

 demolition and material disposal. 



o Consideration will be given to ap- 

 propriate location of parking. 



o Where mangroves are impacted, 

 their associated organisms can 

 move elsewhere. 



o Retaining mangroves on the ocean 

 side will be more important than on 

 the Bay side because of their rela- 

 tive scarcity and wave protection 

 function on the ocean side. 



Many of the foregoing considera- 

 tions can be considered as directed at 

 localized impacts. After release of the 

 negative declaration, FDOT negotiated 

 with concerned natural resource agen- 

 cies about regional considerations. 



Several agencies felt that FDOT 

 was missing a good chance to return 

 the circulation patterns between Florida 

 Bay and the Atlantic Ocean to the pre- 

 vious state that had existed before the 

 Flagler railroad was constructed. As 

 mentioned before, cross-sectional area 

 between islands was reduced more than 

 50% by that project. 



All concerned individuals seem to 

 agree that the salinity difference is 

 real, but that the contribution of the 

 causeway to this situation is not known. 

 Natural physical differences between the 

 two bodies of water are probably a sig- 

 nificant causative factor. Channelization 

 of the Everglades in 1962 

 alterations of fresh water 

 Florida Bay is probably 

 the salinity regime (Davis 



and resultant 

 outflow to the 

 also affecting 

 1977). 



There is definitely not agreement 

 on whether increased flow between the 



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