Great digging by both JDubski and yourself. In the end, it seems that the Sierra Club California/Nevada Desert Committee grudgingly approves of Thacker Pass, given that they accept lithium is required for the transition to non-fossil fuel energy, and that mining by its nature cannot have zero impact on the environment. 

This is another reputable pro-environment source, along with Glenn Miller, that recognizes that in many ways Thacker Pass is uncommon, if not unique, in its potential to produce meaningful amounts of lithium at a relatively low negative impact to the environment. 

I respect that they chose to not participate in the current litigation.