Joshua Tree National Park staff and a team from the University of Vermont will be conducting a historic preservation project on the Lost Horse Mill structure that requires temporary road and trail closure for public safety. Lost Horse Mine Trail will be closed Wednesday, March 27, from 6 a.m. to 4 p.m. Lost Horse Mine Road, off Keys View Road, will be closed from noon on Tuesday, March 26 to 4 p.m. on Wednesday, March 27.