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Indian River County Commissioners Page Two November 19, 1976 The canal under the Site 4 bridge is vegetated by arrowhead, duckweed, filamentous green algae, and water hyacinths. Bottoms are generally mud and are inhabited by orb snails, pond snails and leeches. The area under the Site 5 bridge is vegetated by water hyacinths, duckweed, and filamentous green algae. The bottoms at this site are mud/muck and are inhabited by orb snails as well as other .gastropods and crayfish. An alligator approximately 2 feet long was observed under this bridge, and apple snail eggs were abundant on marsh vegetation. The canal under the Site 6 bridge is vegetated by water hyacinths and two species of duckweed.- The bottoms at this site are mos•:ly mud, and support leeches, orb snails, crayfish, and pond snails. State Road 60 is the upstream limit of Class I Waters in the St. Johns River system. The water in the upper St. Johns Basin is dependent upon sheet flow through the marsh for filtration, nutrient transformation/stabilization and oxygenation, all of which are necessary to maintain Class I water quality standards. The proposed project would effectively reduce sheet flow through the portion of the marsh downstream from SR 60, and result in the channelization of waters through the bridge at Site 3. In addition, the project may have a damming effect, holding waters on the upstream side of the causeway and subjecting downstream portions of the marsh to unnaturally dry conditions. The temporary by-pass.roads can be expected to have short-range detrimental effects, related to turbidity and temporary loss of portions -of t."Ie marsh, but these considerations are insignificant in comparison to the long-term water quality problems which would result from lack of adequate sheet flow of water through the entire marsh. Replacing the existing bridges with bridges of at least equal spans or constructing enough culverts to provide at least the present sheet flow at all locations would help to minimize the long-term impact of the construction. Pursuant to the requirement of Section 253.124(3), Florida Statutes, the preceding comments should be duly considered by the commission and read into the minutes of the meeting at which time determination of local approval is made. Sincerely, A.ea�n Section Admi:,istrator Standard Permitting Section AJT/jss Enclosures cc: Freddy Miller, D.O.T., St. Johns River District Game and Fresh Water Fish Commission EC