Measurement of internal seiche in Lake Chelan, WA

The large internal seiche of the Lucerne Basin of Lake Chelan was described in Pelletier et al., 1989, in short, the rocking back and forth of the deep cold water in the Lucerne Basin. The data for this study was collected in 1986 and 1987 and showed an extreme internal seiche. During the summer of 1987 the amplitude of the rocking of the deep cold water was as much as 70 m and the period was approximately 3 days. The main goals of this study were to a) investigate the internal seiche in more detail than was possible in the 1980’s and b) determine how the seiche interacted with the sill between the Lucerne Basin and the Wapato Basin.

This study is significant to water quality of Lake Chelan in two ways. 1) Without knowing the status of the internal seiche under summer conditions, it is difficult to know the source of waters being sampled, the deep cold water versus the shallow warm water in the lake. Each of these waters typically exhibit different water quality signatures. 2) The interaction of the internal seiche with the lake bottom likely influences the transport of fine sediment, sediment distribution and water clarity in the vicinity of the narrows of Lake Chelan. Without knowledge of the seiche dynamics it will be difficult to interpret secchi depths and related water quality parameters in this part of the lake.

Raw project data will be available in 2020 by contacting [e-mail]