By Michael P. Neufeld
Crestline, CA – The mandated drawdown of Lake Gregory continued Tuesday night with the water level lowered 3-feet from the spillway. The Division of Safety of Dams (DSOD) is requiring San Bernardino County to lower the water a total of 5-feet from the spillway because the 80-year-old Lake Gregory Dam does not meet current seismic safety requirements.
THE REHABILITATION PROJECT
The $16 million project — which could take up to 18 months to complete — includes the removal of trees and vegetation from the downstream slope of the dam, the removal of the existing rock on the downstream slope, removal of foundation material at the base of the dam, the addition of a new 40-foot average thickness earthen buttress extending approximately 62 feet beyond the current toe of the embankment, installation of a drainage system to pick up water moving through the liquefaction zone, and placement of new slope protection.
The project — which has been returned to the Board of Supervisors for revisions several times — requires retrieval and hauling of stockpiled material from up to two borrow sites and import material from quarries in the San Bernardino valley; a temporary bridge reinforcement over Houston Creek in privately owned Camp Switzerland; traffic controls along Lake Drive (including a temporary road detour); temporary or permanent relocation of utilities on Lake Drive and affected portions of Lake Drive.