There's no mention of the pine beetle in the article. He heavily implicates drought and climate change.
It seems like a similar process is playing out in California due to the native bark beetle.
Colorado seems to be doing better these days. I think the pine beetle mitigation efforts are showing some progress and I would assume that the trees left standing are maybe naturally more resistant.
Both are likely related, reduced water makes the trees more susceptible to the ravages of the pests?
Local news site for Tahoe specifically: http://www.tahoedailytribune.com/news/california-tahoe-area-...
SF Chronicle on the beetle problem and commenting on the excess wood: http://www.sfchronicle.com/bayarea/article/California-has-66...
Maybe it is a different kind of beetle, but the article does mention beetles.