"In 2016, of the 115 drivers in fatal wrecks who tested positive for marijuana use, 71 were found to have Delta-9 tetrahydrocannabinol, or THC, the psychoactive ingredient in marijuana, in their blood, indicating use within hours, according to state data. Of those, 63 percent were over 5 nanograms per milliliter, the state’s limit for driving".  

63% of 71 is 47, and 47 is 7.7% of 605 fatal accidents in 2016.

Here is a chart from CDOT that proves beyond any doubt that this issue is wildly overblown as there were more than 600 fatalities in Colorado in 2005, back when marijuana was decriminalized except for medical marijuana patients, and our State population was at-least 500,000 people less than in 2016 too.  It appears that there was a considerable reduction in traffic fatalities and injuries that corresponds with the Great Recession. 

https://www.codot.gov/news/documents/safety-press-conference-boards-jan-31-2017

I am afraid this news item is based on false pretenses.