DUNE 

 STABILIZATION 



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EXPERIMENTAL marsh 



Figure 6.6. The 495-acre restoration plan to return tidal flows to the southern arm of Tijuana 

 Estuary. Excavation to create channels and marsh would avoid ecologically sensitive areas (Figure 

 6.4). A single river-training levee (or berm) would divert sediments from future floods. 



River training levee or berm. The 

 original plan (Figure 6.3, Williams and 

 Swanson 1987) called for two large river 

 training berms, the larger being 2.4 km (1.5 

 mi) long and 18 m (60 ft) high; these berms 

 would consume most of the spoils dredged from 

 the restoration site. Subsequent plans 

 (Florsheim et al. 1991) eliminated the 

 smaller berm and reduced the height of the 

 larger berm to about 8 m (25 ft). It would be 

 about 1.5 km (~1 mi) long and cover 19 ha 

 (46 ac). This size was estimated as the 

 minimum necessary to protect the estuary 

 through a 100-year flood event. 



The berm was designed to be vegetated, but 

 expected to erode with the larger floods. A 

 wide berm would have sufficient sediment to 

 accommodate erosion under most flood 

 conditions. The berm has been an ecological 

 concern, because it is not certain if the spoils 



will support native vegetation. It would also 

 abut native bluffs that support coastal sage 

 scrub and associated rare birds. 



As an alternative, a levee was designed that 

 would be lower (3 m, 10 ft) and narrower 

 (30 m, 100 ft) and cover much less ground 

 (5 ha, 12 ac; Entrix et al. 1991). The choice 

 between a levee and a berm awaits further 

 environmental review and results of research 

 to be conducted on an experimental berm. 



• Dredge spoil disposal. Dredging at 

 Tijuana Estuary will generate spoils that 

 differ in quality, depending on their source 

 and presence of contaminants (to be assessed 

 in a detailed sampling program). Sandy spoils 

 may be used to replenish the beach and dunes, 

 but spoils of low quality will be taken off site. 

 Whether they are suitable for disposal on land 

 will depend on their quality. High salinity 



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