6
Dredging Plan
Recommendations
The highly dynamic nature of Chatham Inlet has presented a challenge in
maintaining safe navigation through shifting shoals and channels. Although the
inlet evolutionary processes are still not completely understood, this study has
undertaken to examine development of the major shoreline and shoal morphology
and identify patterns of change in a seemingly chaotic growth over 13 years since
inlet formation.
There were two areas of difficult navigation due to shoaling and shifting
channels. The first area was in the north and south main ebb channels, particularly
where they cross the terminal lobe of the ebb shoal. The changes in the swash bars
on the swash platform near the shifting channels also have presented hazards to
navigating a safe passage into the Atlantic Ocean.
A second problem area was in maintaining a reliable navigation channel in
the vicinity of the west flood channel and entrance channel for the Town of
Chatham's commercial fishing fleet and U.S. Coast Guard vessels anchored in
Aunt Lydia's Cove. Shoaling associated with the growth and evolution of the
north flood shoal, Tern Island, and Tern Island south shoal resulted in large
changes in the depth and orientation of these two channels.
Dredging History
Ten separate channel dredging operations have been done since 1989 to
maintain access to the Fish Pier anchorage (Table 5). The first four were done by
local interests through a private contractor, but were not well documented. Sub-
sequent operations dredged either the entrance channel between Tern Island and
Tern Island south shoal, parts of the anchorage in Aunt Lydia's Cove and later the
west ebb spit of the north flood shoal to connect the anchorage to the west flood
channel. The U.S. Army Corps of Engineers first received authorization for the
Aunt Lydia's Cove Project on 31 August 1994 under authority of Public Law 86-
645, Section 107, as amended. This existing project provides for dredging of an
entrance channel 8 ft (2.4 m) deep and 100 ft (30.5 m) wide for a length of 900 ft
(274 m), and a 9.5 acre (38,446.5 m2) anchorage also to a depth of 8 ft (2.4 m).
Figure 54 shows the boundaries in blue of the 1994/95 dredging operation,
completed in June 1995. More than 100,000 cu yd (76,460 m3) of sand were
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Chapter 6 Dredging Plan Recommendations
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