I have a similar story in my family's past. In the 40's my grandfather bought a large farm that he raised hundreds of hogs on, and made hay. At some point he bought most of the neighbor's farm also, bringing the acreage total to over 400. Then in the mid 50's the Army Corps came through and said they were going to put in a dam to control watershed, to help with flooding in Pittsburgh (150 miles downstream). They wanted 370 acres of his farm, which they said would then be underwater. They handed him a check, which he fought with them over the value, and it was a take it or take nothing offer.
Long story short, the family farm was knocked down to just 30 acres. They built the dam and the water never did reach up to his property. Now that land all around the new lake is labeled \"park land\". It is all overgrown with thorn trees and briars, what used to be his beautiful hay fields. But oh well, there was nothing that could be done.
I hope your situation fairs better than my grandfathers.