Arena Plains NWR ist part of the San Luis and Merced NWR. Arena Plains normally is not open to the public.
http://www.fws.gov/sanluis/arena_plains.htm
This refuge consists of 2,464 acres and contains the San Joaquin Valley's largest block of undisturbed sand dunes, perched wetlands, and vernal pool habitat.
Unique wildflower fields plus a variety of endangered, threatened and sensitive wildlife and plants exist here.
Once a year the public is welcome to ranger led tours. On April 10th 2010 I participated in the tour, and these are my photos from that day.
Rangers give instructions
Rangers give instructions