Stan and Richard - thanks so much on the great kayak advice. I am brand new to this, and am using a sit-on-top which seems remarkably stable, even when shooting; as I am unable to keep a classic kayak upright in a bath tub, this has been reassuring.
I only started late this season but have found that it is impossible to approach ducks at all - they disappear as soon as they see a boat hundreds of yards away. Maybe sneaking them will work better early in the season next year. Fortunately, our lawn-fed Canada geese are more gullible.
LD, I have hunted the Alviso ponds a few times this year, but it has been very slow - only a few ruddies and buffleheads flying, but a gazillion waders, terns, egrets, pelicans, etc. We have had virtually no weather this year, northern ducks never arrived, and the locals got wise in November.
However, being all alone in a vast salt marsh 15 minutes from home sure beats driving to the Central Valley and lining up with hundreds of guys in a 4 AM sweat line.