Born again

Abstract

Dam erosion at the Lake Ilo dam in the USA made failure a distinct possibility. Lake Ilo's function original function was to provide a refuge for wildlife and migratory birds. The US Fish and Wildlife Service (FWS), the owner of the dam, cut a 2.1 m deep notch in the ogee crest to reduce reservoir levels and seepage pressures on the dam foundations. The lower reservoir level created a mudflat habitat that attracted large numbers of migratory birds. Extensive archaeological sites were discovered. GEI Consultants were retained to examine the options and to work on the project. Dam rehabilitation was selected. Modifications included embankment improvements, the addition of an emergency spillway, removal and replacement of the existing spillway and construction of new low level outlet works.