I've edited my post a bit..
anyway, no matter what I said, I wouldn't myself want to put up a fence (I don't think.) You can tell I'm thinking as I type. When I first lived in northern California, I hadn't bought a house yet, and my real estate agent got me a 4 bedroom tract (but sort of nice) house to live in, amazingly cheap rent if I would keep the house heated for the winter, and have a place while I house hunted. (I only lived there a month, in that house that hadn't sold for three years, another story, the buyers loved it). That place had a deep back yard of sequoia trees, truly beautiful, and the property to, uh, the west of that house's, was grassland and a few trees, and, that first day, three deer. That was quite a welcome. My point is they had a low fence, let's say 42" high between the rental house and the grassland and further housing. It showed the property line, but even an old and crotchety deer could have easily gotten over it. (I get concerned that in CA we have lost a lot of our wildlife corridors.)
Glad that's a dedicated wetlands, good. I'm now assuming that means no fence, I think that's good too. I wonder though about survey markers or some kind of not too awful sign.