National parks halt mowing after fatal Asheville accident
Worker's death near Asheville prompts federal probe
http://www.citizen-times.com/article/B0/20120515/NEWS/305150011/National-parks-halt-mowing-after-death-near-Asheville?odyssey=nav%7Chead
A seasonal worker died after running his riding mower off a near vertical embankment. The NPS is halting all lawn moving across all units until each unit can provide a review of safety practices regarding lawn moving.
I don't think there are a whole lot of lawns in Yosemite that are an NPS responsibility. I'm pretty sure the order doesn't bar DNC from mowing the lawn at the Ahwahnee or maintaining the Wawona Golf Course (is it open yet?).
This could get interesting. NPS maintains several lawns in the Bay Area, including the ones at the Presidio (including the rather huge lawn at Chrissy Field that used to be the airstrip), picnic areas at Point Reyes, and Fort Mason. Quite a few visitor centers have small lawns that only require a small push mower. I know there's criticism over the state of maintenance at the National Mall, but it could get really nasty if it doesn't get cut.