This just in from the US Forest Service, the quick reply was much appreciated.
Thank you for your inquiry regarding the closure date for Blackwood Canyon. The road report that I was given by our Engineering/Roads department gives a closure date of November 15. However, these dates are tentative, subject to change at any time, and weather dependent. If we receive significant amounts of rain or snow the gate may closer earlier. Public Affaris Specialist, USFS Lake Tahoe Basin Mgt Unit