How might the damming of a river affect an estuary at the river'smouth?
Since this is not my area of expertise, I searched Google under the key words "estuary 'river dam'" to get these possible sources:
http://pubs.usgs.gov/wri/wri004124/
http://www.gnb.ca/0099/eelRiverDam/e/spring_Fieldwork_2004.pdf
(Broken Link Removed)
(Broken Link Removed)
http://www.answers.com/topic/link-river-dam
In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search.
I hope this helps. Thanks for asking.