LAC has filed their response (26th July) to the Motion to Intervene sought by some Tribal members. A link to the document was provided by @domesticsupply on twitter, for those that would like to read it.
They argue (amongst other things) the Motion is untimely, and allowing an intervention would be prejudicial to LAC and would set a dangerous precedent that would be difficult/impossible for federal agencies to follow in the future.
The arguments put forward by Ms. Granier (LAC Attorney) are quite compelling. I wish there was two of her, so she could represent the BLM as well.
I expect the Motion will be denied in time for the historic/cultural survey work to commence on or about 29th July, as planned.