ABSTRACT

White Lake is the largest natural lake in southwestern Louisiana. It initially formed by mudflat and marsh subsidence during the development of the chenier plain which borders to the south. The closest major chenier, Pecan Island, has been dated at approximately 1,250 years B.P.

Although regional subsidence and the accompanying enlargement of White Lake continue at a slow rate, the recent history of the lake documents especially well the effects of navigation on shoreline retreat. Between 1940 and 1951, the northern, eastern, and western margins of the lake remained virtually unchanged. Increased navigation in White Lake accompanied new oil and gas operations in the region in the post-1950 years. Seafood harvesting also burgeoned. Over 300 m of shoreline retreat due to waves from boats and disturbance of bottom sediments by propellers had occurred by 1988.

Most vessels enter White Lake from the east via Schooner Bayou (the "old" Intracoastal Waterway), and then turn to the southwest. As a result of this vehicular traffic, the shore of White Lake just south of Schooner Bayou retreated eastward 60 m between 1951 and 1964, 53 m from 1964 to 1975, 98 m between 1975 and 1980, and 105 m from 1980 to 1988. This total of 316 m of retreat in just 37 years is a very rapid rate. In contrast, the shore north of Schooner Bayou, which has been affected less by navigation, has retreated 155 m during the same period.

Interference by man, rather than natural processes, is thus the dominant factor contributing to the current enlargement of White Lake. Unless protective measures are instituted, the rapid rate of shoreline retreat and marsh deterioration will continue virtually unchecked.

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