1. Gibson County Surveyor
Legal Aspects of County Boundaries Understanding your County’s Description and Riparian Rights
Michael Stevenson, P.L.S.
Gibson County Surveyor

2. Gibson County’s Description
"Beginning on White river where the line dividing ranges nine and ten crosses the same, thence down the said river to its junction with the Wabash river, thence down the same to where the line dividing sections twenty-eight and thirty-three, township three south, range fourteen west, strikes the same, thence east to the line dividing ranges twelve and thirteen west, thence south to the line dividing townships three and four south, range twelve west, thence east to the line dividing ranges eleven and twelve west…

3. River Boundaries

4. River Boundaries
County lines will move with the river in most cases…with a few exceptions.

5. River Boundaries Accretion
Derived from the Latin “accrescere” which means to grow or increase. It is the gradual and imperceptible addition of soil or other material by the natural processes of water-borne sedimentation or by the action of currents against shores and banks.

6. River Boundaries Erosion
In riparian law, the washing away of land by the sea or a river’s flow. Usually considered an imperceptible action, the rate of erosion may be quite rapid in total effect.

7. Note: For GIS purposes, median should work
River Boundaries
State Line vs. County Line
Thalweg vs. median
Note: For GIS purposes, median should work

8. River Boundaries Avulsion
A river’s sudden change in flow alignment out from its previous left and right banks to a new channel, leaving an identifiable upland area between the abandoned channel and the new channel. The new flow alignment will generally be a shortcut in channel length. Boundary does not change.

9. River Boundaries
Man-made Avulsion

10. Navigable River Ownership
As a side note, ownership of navigable rivers (classified as of 1816) in Indiana are owned by the State of Indiana – ordinary high water mark to ordinary high water mark.

11. Gibson County Surveyor
Michael Stevenson, P.L.S.
Gibson County Surveyor