The significant amount of sloughing that could occur on the slopes next to the proposed Site C reservoir is a major area of concern. There is considerable instability in some of the slopes in the identified area, as can be seen by past slides that have occurred. The Attachie slide of 1973 is a notable example, in which the Peace River was blocked for approximately 10 hours. Another slide that extended 1.5 miles across occurred on the north bank just downstream of Cache Creek.
The Thurber report also includes the safeline maps from 1976 and, to my knowledge, nothing more current has been made available. It appears to me that BC Hydro has gone through the “consultation” process without being able to give the public an accurate illustration of how much and who’s land will be potentially affected. These safeline maps illustrate that the potential sloughing is anticipated to extend over a mile back at some locations.
They can be viewed larger by clicking on the following: safeline3, safeline4, safeline5. In addition, the safeline maps’ legend can be viewed here.
Reference to the Thurber report,
Sites C and E Hydroelectric Development Proposals: Lower Peace River Environmental Study. Sept. 1976. Volume II: Impact Assessment of Basic Alternatives – Part of a Report to BC Hydro and Power Authority