I was always curious as to the origin of the side channels Rudi and I found in the Conroy Marsh on our paddling trip several weeks ago. They had at least the semblance of being man-made from our perspective on the water, as they were too uniform in width to be natural, and clearly on the aerial view courtesy Google Earth as they stand out distinctly, and no other feature similar to these three ring channels can be found in the Marsh.
I accidentally stumbled upon the answer a few days back, and as it turns out, Ducks Unlimited Canada dredged the channels back in 1982 as some purported method of aiding duck breeding in the marsh (perhaps preventing four legged predators getting at them - But how is that fair?). If you look closely at the photo I have included, the channels were dredged around existing natural hillocks, the south end of the largest being a mammoth slab of granite rising twenty feet out of the Marsh. In any event, there appeared to be some negative aspects to the program, and the dredging was discontinued, whether or not more was planned for the Marsh.