[EBB Sightings] Where to see Thayer's Gulls?

Does anyone know of a good spot in the East Bay (preferably north of the
Bay Bridge) to see and observe Thayer's Gulls? I know it's getting to be
late and that they'll be departing the area soon, but it's a species
that I'm trying to become more familiar with. I've only seen a few in my
years of birding (all near the immediate coast) and would simply like to
be able to study some individuals so I'm more comfortable picking them
out of an average gull flock. Feel free to email me off-list if you have
any suggestions or advice.

On a somewhat related side note, I stopped by the Richmond (aka. West
County Wastewater Treatment Plant) sewage ponds northwest of Richmond
Parkway and Pittsburg Ave. late yesterday afternoon...didn't see any
Thayer's Gulls, but there were a lot of Mew Gulls and Ring-billed Gulls
of various cycles. A few Ring-billed Gulls had even molted into
alternate plumage. Also of interest were several American Avocets in
alternate plumage, Black-necked Stilts, and several Gadwall at the
western end of the pond. A few adult Glaucous-winged Gulls were roosting
on the berm along the northern edge of the pond when I first arrived,
but had departed by the time I left.

Matt Ricketts
El Cerrito