Reservations will be available May 15, 2018 on Recreation.gov 

Yosemite National Park announces that parking reservations will be required for all buses over 20 feet in length, including commercial tour buses, non-commercial buses, and mini-buses, to park and visit the Mariposa Grove of Giant Sequoias. The Mariposa Grove will reopen to the public on Friday, June 15, 2018.  Bus reservations will be available beginning at 7:00 am PDTon Tuesday, May 15, 2018 on Recreation.gov for the summer and fall seasons from June 15, 2018 through November 30, 2018.
Four parking spaces for buses will be available for buses over 20 feet in length at the Reserved Bus Parking Area when the Mariposa Grove of Giant Sequoias reopens to the public. This Reserved Bus Parking Area is located across from the existing South Entrance restroom (on the upper side of the Mariposa Grove Road).
Bus parking reservations will cost $1.50 and will be non-refundable. Companies, organizations, and individuals will be able to book a maximum of 2 bus reservations per day. A maximum of 6 bus reservations may be booked within a single logon session. Reservations are for 3-hour blocks. Operators cannot exceed the 3-hour parking limit.
Reservations will be available daily during the summer within the following 3-Hour time blocks:

Buses dropping off/picking-up passengers will be directed to enter the left lane of the shuttle bus loop at the Mariposa Grove Welcome Plaza. All passengers and tour guides will have access to restroom facilities, visitor information, and will board a free shuttle for the two mile ride to the Mariposa Grove of Giant Sequoias Arrival Area. Shuttles will operate on a first come, first served basis so tour groups may be temporarily split up until they can regroup in the Grove Arrival Area.
As soon as a bus has unloaded, the operator will make a left turn and proceed to their reserved parking space in the Reserved Bus Parking Area. Here, drivers can wait until their guests are ready to be picked up from the shuttle loop. Buses will not be permitted to park or idle in the Mariposa Grove Welcome Plaza shuttle loop area.
Buses that do not have a parking reservation will not be allowed to drop off their passengers to visit the Mariposa Grove of Giant Sequoias during their visit to Yosemite.
School groups planning to visit the Mariposa Grove of Giant Sequoias as part of their visit to Yosemite National Park should contact the Education Fee Waiver Office for information on school bus passenger drop-off locations and parking at e-mail us.
The Mariposa Grove of Giant Sequoias will be reopening this June, marking the completion of a $40 million restoration project. This ambitious restoration project, in partnership with Yosemite Conservancy, sought to restore the Mariposa Grove of Giant Sequoias by removing a parking lot at the base of the sequoias, removing commercial facilities, and restoring the hydrology to ensure that new trees can grow in a healthy environment. Additionally, a new parking area and welcome plaza have been constructed at the park’s South Entrance to welcome and shuttle visitors back and forth to the Big Trees.