The nest at Ken Reid Conservation Area is active and is well worth the trip if you can make it out. Just follow the marsh boardwalk to the lookout and you'll see it just off to the right. You can get a great view of the marsh and there's almost always a pair of Great Blue's stalking in the marshy areas as per the photo below and I saw several ducks but they were too far away to id as I only had the camera with me.
Cheers, Attila