Tuesday, April 24, 2012

Kāne‘ohe Bay Dredging

The earliest modifications to the natural marine environment of Kāne‘ohe Bay were those made by the ancient Hawaiians.

The construction of walled fishponds along the shore was perhaps the most obvious innovation.

The development of terraces and a complex irrigation network for the cultivation of taro no doubt had an effect on stream flow, reducing total runoff into the Bay.

In general, however, it can be stated that these early changes did not greatly modify the marine environment that existed when man first arrived in the area.

However, dredging in the Bay did.

Records of dredging permits issued by the Army Corps of Engineers begin in 1915.

Almost all of the early permits were for boat landings, piers and wharves, including the 1,200-foot wharf at Kokokahi and the 500-ft wharf at Moku-o-Loe (Coconut Island) for Hawaiian Tuna Packers (in 1934.)

Although some dredging was involved in the construction of piers and small boat basins, probably the first extensive dredging was done in 1937 when 56,000 cubic yards were dredged "from the coral reef in Kāne‘ohe Bay" by the Mokapu Land Co., Ltd.

The great bulk of all reef material dredged in Kāne‘ohe Bay was removed in connection with the construction at Mokapu of the Kāne‘ohe Naval Air Station (now Marine Corps Base Hawai‘i) between 1939 and 1945.

Dredging for the base began on September 27, 1939, and continued throughout World War II.  A bulkhead was constructed on the west side of Mokapu Peninsula, and initial dredged material from the adjacent reef flat was used as fill behind it.

In November 1939, the patch reefs in the seaplane take-off area in the main Bay basin were dredged to 10-feet (later most were taken down to 30-feet.)

Other early dredging was just off the northwest tip of the peninsula, near the site of the "landing mat" (runway.)  The runway was about half complete at the time of the Japanese attack on December 7, 1941.

It appears that a fairly reliable total of dredged material is 15,193,000 cubic yards.

(Do the Math … Let’s say the common dump truck load is 10 cubic yards … that’s a million and an half truckloads of dredge material.)

During the war there had been some modifications of the ponds on Mokapu Peninsula, but the shore ponds around the perimeter of the Bay were spared.

However, from 1946 to 1948 (mostly in 1947) nine fishponds with a total area of nearly 60 acres, were filled, eight of them located in Kāne‘ohe ahupua‘a in the southern portion of the Bay.

In the Great Māhele, Hawaiian fishponds were considered private property by landowners and by the Hawaiian government.

This was confirmed in subsequent Court cases that noted “titles to fishponds are recognized to the same extent and in the same manner as rights recognized in fast land.”

Many of the filled fishponds were developed into residential uses (I’ll have more on fishponds in general and some specific ones in future posts.)

There are now only 12 walled fishponds remaining of the 30 known to have once existed in Kāne‘ohe Bay and a number of these have only partial remains and are not immediately recognizable as fishponds.

The image shows the dredge machine near the Marine base runway, just before the start of WW II.  (Much of the information here is from Kāne‘ohe, A History of Change.)

1 comment:

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