Scripps Institution of Oceanography

The protracted construction activity at San Onofre Nuclear Generating Station (SONGS) over the 20-year period from 1964 to 1984 caused significant changes in the local beach configuration. In particular, large quantities of sand supplied from cliff and offshore excavation contributed to substantial long-term, though temporary, beach widening. The occurrence of unusual flooding in the winters of 1978, 1980 and 1982 also contributed substantial quantities of sand to the area.

The construction of laydown pads, especially the long-lived pad in existence from 1974 to 1984 used for Units 2 and 3 construction, interrupted the longshore flow of sand and caused substantial widening of the local beaches, especially north of the plant. After removal of the pad, the sand trapped behind it seems to have bifurcated into two bulges that have remained relatively close to the site, consistent with directional wave observations.

Relatively rapid retreat of the beach has been observed directly in front of SONGS, and to a lesser degree to the north. As longshore and offshore wave induced transport continue over the coming years it is reasonable to expect that the local beaches, including the upcoast state park, will revert to their relatively narrow, pre-1964 condition.