ABSTRACT

Icy Bay is the only sheltered bay near many of the offshore tracts that were leased for petroleum exploration in the April 1976 northern Gulf of Alaska OCS lease sale. Consequently, it has been selected as a primary onshore staging site for the support of offshore exploration and development. The environment of Icy Bay has many potentially hazardous features, including a submarine moraine at the bay mouth and actively calving glaciers at the bay's head which produce many icebergs. But most significant from the point of view of locating onshore facilities and pipeline corridors are the high rates of shoreline erosion and sediment deposition.

The glacier that once filled Icy Bay has receded more than 40 km since 1904, when the bay was completely ice covered. A large hooked spit, Point Riou Spit, has developed on the eastern shore of the bay mouth within the limits of the terminal moraine and has grown to a length of 6.6 km (an average growth rate of 92 m/y). The Gulf of Alaska shoreline on the east side of Icy Bay, which includes the Malaspina Foreland and Point Riou Spit complex, has been steadily eroded northward by waves and long shore currents. Analysis of ten sets of aerial photographs taken since 1941 indicate that the eastern shoreline has receded as much as 1.3 km in this 35"year period, an average rate of retreat of 37 m/y. The western shoreline has also changed similarly; over 8.2 km2 have disappeared, including all of Guyot Bay.

Field observations during 1976 revealed that the eastern section of Point Rioll Spit is frequently washed over by storm waves and is filling in the Riou Bay portion of Icy Bay with sediment. At the point where the spit attaches to the Malaspina Foreland, a forest with trees at least 90 years old is being undercut by wave erosion. If pipelines or any onshore staging facilities are to be placed in the areas of Point Riou, Riou Bay, or the Malaspina Foreland, then the dynamic changes in shoreline position must be considered so that man-made structures will not be eroded away or silted in before the completion of development.

INTRODUCTION

Icy Bay, Alaska (Fig. I), a north-trending fiord adjacent to the Gulf of Alaska, lies 20- 80 km from the majority of potentially rich offshore tracts leased in the April 1976 Northern Gulf of Alaska Lease Sale (OCS Sale #39). It also offers the only shelter from storms for marine traffic between Yakutat Bay 90 km to the east and Prince William Sound 295 km to the west. Its location and the protection it can offer have made it a logical candidate for consideration as an onshore staging area for the development of Gulf of Alaska oil and gas.

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