SECTION V 

 SAFE HARBOR 



BATHYMETRY 



Safe Harbor is a man-made harbor built primarily for the shrimp 

 boat fleet. It is divisible into four parts; an approach channel, 

 turning basin, entrance canal, and series of embayments for docking 

 boats. It was built in several stages between 1950 and 1960 (Fig. 6). 

 Except for some of the inner basins the harbor was dredged to a depth 

 of about 30 feet (9m) by shore-operated draglines. 



The gently undulating floor of the harbor is covered with fine calcium 

 carbonate silt and the vertical walls are coral rock encrusted with 

 various organisms. Figure 9 shows the bottom topography as deter- 

 mined from fathometer tracings. The average depth of the harbor 

 and turning basin is 22.6 feet (6.89m). Depths of 35 feet (10.67m) 

 are found in two of the marina basins and in the turning basin. 

 Thirty-foot (9m) depths occur in all marinas and along the edges of 

 the entrance canal from the southern side of the City Electric dock 

 to the turning basin. All of the 30-foot (9m) deep basins are 

 surrounded by shallower bottom. They communicate with each other 

 above the 25-foot (7.62m) level but are cutoff from the open sea by 

 an 18- foot (5.49m) sill in the channel dredged across the shallow 

 flats to the south of Stock Island. Thus, the water within the turn- 

 ing basin and harbor ac depths greater than 18 feet (5.49m) circu- 

 lated poorly. 



WATER CIRCULATION 



During the study, winds from the southeast moved surface water into 

 the harbor. Most of this water, and water brought in by the flood 

 tide, came from flats to the east of Safe Harbor. Current flow in 

 deep water in the entrance canal was predominantly out of the harbor- 

 On some spring flood tides, the current reversed on the bottom or 

 stopped completely. Currents were imperceptible in harbor embayments 

 at depths greater than 30 feet (9m) and anoxic conditions occasionally 

 occurred. Surface currents inside the harbor and on adjacent shallow 

 water flats were wind-driven with little or no tidal influence. Clarke 

 et al (1970) provide additional wind and current data for Safe Harbor. 



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