This is a real easy find, you might have to look a bit but then
you'll wonder how you missed it before.
There is a gate across from the entrance to
the East side of this area at (N 39 08.840 W 121 18.737) but it
like the fence is made of barbed wire.
Beware, depending on where you park there
are few gates within a decent walking distance.
The barbwire fence (for the Spenceville Area) are there to keep
vehicles out not people
(The POC is Tim Caldwell, the manager for
the CA Fish and Game concerns for Spenceville (530)
624-8658).
You must practice non-destructive methods for crossing it though,
perhaps a thick material to avoid any scrapes or
scratches.