I will expand on this:
Panama Flats has a number of access points depending on what habitat you are targeting.
For Marsh/flooded field access, the trail head at Carey Rd/Baker St. near the grey farm shed gives quick access to the Central Dikes and south trail. Parking on Baker St and side streets. Best in the morning.
The Hyacinth Park lot of Hyacinth Ave./Interurban allows you to walk in from the south to get a mix of Riperian transitioning into Marsh, also you can check out the Swan Creek near the parking lot. Barred Owl have been known to hang out in the willows and rare birds have turned up here as well (people tend to forget this portion so not as well birded)
To the north, parking along Roy Rd. offers good access to the Panama Hill rock outcrop and is better for evening viewing of the flats (sun behind you). Again, an area/habitat not to be neglected. The few oaks and open riperian areas can be really good, especially when the berry crop is ripe. Better for sparrows, warblers, goldfinch.
Panama Flats is a big area to bird and I am sure people are missing species as they are focused on the marsh/central dike area.
Cheers and good birding,