Bit more reading
http://www.margaretrivermail.com.au/news/local/news/general/blackwood-river-mouth-opening-strategy/1575168.aspxwww.margaretrivermail.com.au/news/opinion/letters/general/put-the-cut-in-the-rivermouth/1649728.aspx"The rivermouth has moved 2km east of the Colour Patch, raising concern about the estuary's water quality and flood risk.
The rivermouth has been moving to the east for many years, noticeably in the mid-1920s and late-1970s,
creating a sand spit to the east of Dukes Head.In March 1945 it became blocked, possibly due to the low tidal exchange combined with onshore sand movement.
Winter river flows were trapped and the river level rose up to 2m, causing flooding.
Three local men used a horse-drawn scoop and shovels to cut a channel and clear the sand spit, returning the mouth to its historical position."
"The westerly location was chosen as the most likely to provide the longest time before intervention is needed again, and the greatest short term gains in water quality in the lower estuary."