Teaching about marshes and wetland at Martinez shoreline park

We went on a field trip last week to the Martinez Regional Shoreline in Martinez, CA.  There is a beautiful path through the marsh and wetland, and lots of wildlife to view.  I highly recommend this as a place to stop by on the way to the John Muir National Park.

Before going here, I would recommend doing some homework on marshes and wetland.  I found a website that was even educational to me!
http://education.nationalgeographic.com/education/encyclopedia/marsh/?ar_a=1

I am still looking for books I would recommend for children about wetlands.