There are a few small ponds. The birds here seem to be pretty used to people walking around...so you can get close and get some pretty good shots.
For more information about directions, hours of operations visit the discovery park web site
They also have a photo contest going on if you are interested.
The ponds in discovery park are located close to the North parking lot. Sunset is usually a great time to take pictures of the birds.
Lat, Long : 47.665190, -122.412310
Map of discovery park
Equipment used: Canon 20D, Canon 100-400L. The image stabilizer works :) I shot this without the tripod...