4.4 Biological Resources
distances where hard substrate is either mapped or indicated by commercial fisherman. The indirect
sediment impacts under this alternative would be the less than significant.
Potential Indirect Sedimentation Impacts Near North Carlsbad. Under Alternative 2, there would be
no replenishment at the North Carlsbad receiver site, but a greater amount would be placed at the South
Oceanside receiver site and that greater amount would be configured differently. Under Alternative 1, the
total replenishment amount at South Oceanside and North Carlsbad would be 620,000 cy, while under
Alternative 2 the total would be 570,000. Sediment transport would continue to be toward the south,
although 50,000 cy less sand would be introduced to the system overall, that sand would be less likely to
erode from the South Oceanside receiver sites at as fast a rate and it would have farther to travel to reach
the North Carlsbad sediment risk area. While the potential for worst-case, indirect sedimentation would
certainly be less at this location under Alternative 2 than under Alternative 1, the transport patterns under
this alternative have not been modeled and it is difficult to predict with certainty how much less. Under
Alternative 1, an area of approximately 0.13 acre of surfgrass and 0.73 acre with giant kelp would receive
partial sedimentation based on worst-case model predictions. Under Alternative 2, the area to experience
partial inundation would be less, but this analysis does not speculate how much less. In either case, the
indirect impact would be less than significant.
Potent ial Indirect Sedimentation Impacts Near Batiquitos/Moonlight Beach. Under Alternative 2
neither of these two receiver sites would receive sand, nor would the Leucadia receiver site located in
between these two locations. Because there would be no sand introduced in this area of the coast, there
would be no potential indirect sedimentation impacts under this alternative.
Potential Indirect Sedimentation Impacts North of Solana Beach and North of Del Mar. Under
Alternative 2, these two receiver sites would receive the same amount of replenishment material as under
Alternative 1 and the potential impacts would be identical. The area of sedimentation risk off Del Mar is
characterized by cobble and rock relief with no sensitive indicators. There would be no significant impact.
North of Solana Beach there is the worst-case potential for sedimentation to result in partial sedimentation
on two reefs (totaling approximately one acre) with both sparse juveniles and giant kelp. The temporary
loss of kelp in a non-persistent kelp bed area would not be a significant impact.
Summary of Indirect Sedimentation Impacts. Under Alternative 2a, worst-case, conservative estimates
of partial sedimentation impacts total just over two acres. Near North Carlsbad, potential impacts could
occur to less than 1.73 acres with giant kelp and less than 0.24 acre with surfgrass. This acreage amount
Regional Beach Sand Project EIR/EA
Page 4.4-49
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