We have problems with silting also and have had to dredge twice. I suppose perhaps we are fortunate to be able to block the inlet and outlet to do that. The original excavator who dug it had a penchant for islands and even though we specifically told him no island, he left us one anyway. It just makes it look smaller in my mind, and is that much more shoreline to slough off. Serves no particular purpose other than a haven for weasels.
