Hills; and a fourth opposite the Shinnecock Indian Reservation. Three of the breaches closed by 

 the end of 1938, but one stabilized and continued to widen until it was over 200 m across in 

 1939. In 1941, the inlet was 300 m wide, an inner and outer bar had formed, and a tortuous 

 channel connected the Atlantic with Shinnecock Bay. Although in places the channel was over 

 6 m deep, the controlling depth was only about 1 .2 m. 



Construction and Project Work 



Various revetments and jetties have been built at Shinnecock Inlet since 1939. To stabilize 

 the shore and reduce inlet migration, the first bulkhead was built by Suffolk County along the 

 west side of the inlet in 1939. The bulkhead deteriorated and a 243-m stone revetment and 40-m 

 groin were built in 1947 by local and State agencies. Stone rubble-mound jetties were finally 

 built during 1953 and 1954 by the State of New York, Suffolk County, and the Town of 

 Southampton. The east jetty was 415 m long and the west 260 m. The jetties deteriorated over 

 time, with much stone loss occurring at the tip of the east jetty. Though the inlet became a 

 Federal project in 1960, the jetties were not rehabilitated until 1992 and 1993. Chronological 

 details of construction are listed in Appendix A. 



Flood Shoal Development 



The flood shoal experienced slow growth from its beginning in 1938 until 1953, when 

 construction of the jetties began (McCormick 1971). Between 1950 and 1955, the shoal grew 

 rapidly, approximately doubling its size. The rapid growth was caused by the increasing size of 

 the inlet, but growth slowed after 1955 because of the gradual constriction of the size of the tidal 

 channels that crossed the flood delta. The west portion of the shoal was stabilized by the spread 

 of salt-marsh grasses. While the west area was stable after the mid-1950's, the northern margin 

 of the shoal continued to grow into the bay. McCormick estimated the flood shoal growth rate 

 between 1955 and 1969 to be 45,000 nvVyear (59,000 ydVyear). We have no data to verify if the 

 shoal has continued to grow. 



Ebb Shoal Development and Inlet Morphology 



1933 Morphology 



The most complete pre-inlet regional hydrography was collected by the USC&GS in 1933 

 (Atlantic Ocean: charts H-5324 and H-5325; Shinnecock Bay: chart H-5323 (Leatherman and 

 Joneja 1980)). These data are conveniently available from the National Geophysical Data Center 

 on CD-ROM and have been used in this report to depict the baseline conditions in the area. The 

 1933 tracklines are not as tightly spaced as lines in more modern surveys but still are surprisingly 



1 2 Chapter 2 Geologic Setting and Morphologic Development 



