Tolt Dam Failure Warning System

Tait Dam is an approximately 200 ft high, earth embankment dam, and was constructed in the early I 960's. The dam is located on the South Fork Tolt River, northeast of Seattle, and is about 16 miles upstream from the rural community of Carnation, Washington. The dam and 56.000 acre-ft reservoir are major elements of the City of Seattle's water supply system.
In 1979, Seattle City Light (SCL), the City of Seattle's power authority, proposed building a powerhouse and penstock as an additional feature of the Tolt Dam project. As part of the development process, SCL held a series of community meetings in Carnation. While the community supported SCL 's project, it had extensive safety concerns about the dam itself. Around the same period of time, a significant earth slide had occurred downstream of the dam. This created a very muddy condition in the river that was observed further downstream by the citizens of Carnation. In response to their general safety concerns and their perception that the slide had something to do with the dam's condition, Seattle Water Department ( SWD ). the operators of the remote. normally unattended dam, immediately installed a Failure Warning System. comprising available, basic monitoring and emergency warning equipment.