I suspect the law depends both on the river and the state.  I have heard stories about my great-grandfather whose property was bordered by a stream.  He and his neighbor on the other side of the stream had a running battle.  They would put debris in the river in an attempt to change its course.
The property line was the stream and if the stream changed, they ended up with more/less property dependng on how it changed.

I think you need to err on the side of respecting private property rights, especially of the owners have marked the property as such.  If unsure, assume it is private and move on.

I just found this on the Nebraska Game and Parks Commission site. "Remember: Only the water belongs to the state of Nebraska. The stream beds and all adjacent lands are the property of the landowner through which the water flows. Appreciate the fact that you have the privilege of using the waterway. Nebraska statutes give you the right to portage around fences and other obstructions; however you are responsible for any damage you may do.  You must have the landowner's permission to picnic or camp."  So I guess a landowner could chase you off a sandbar in the middle of the Platte since it is his property allthough that seems very unlikely ???  Loading under a bridge should not be a problem since that should be within the R.O.W. of the highway?? Should be about the same for most states??

Just found this on an Iowa Paddlers club's site... interesting... sounds like in Iowa, the "high water mark" law only applies to the lower portions of river where they become much larger...



"In Iowa, on those rivers designated as meandered (see list below), the state owns the stream bed up to the normal high water mark. On those designated as non-meandered, the state owns the water only, and the adjacent land owners own the stream bed.

It's often said that if you step out of your boat on a non-meandered river, technically you are trespassing. This may not be so, as this could be considered a part of "navigating" (see below). But it's never been tested in court.

There are (portions of) 13 interior rivers classified as meandered:

Cedar, lower 157 miles beginning near Cedar Falls
Des Moines, 278 miles, mouth to confluence of east & west forks
East Fork DM, mouth to north edge of Algona, 39 miles
West Fork DM, mouth to Emmetsburg, 44 miles
Iowa, lower 123 miles beginning west of Marengo
Maqouketa, lower 26 miles beginning near Maquoketa
Little Maquoketa, lower 2 miles
Nishnabotna, lower 6 miles
Raccoon, mouth to Dallas-Polk County line, 13 miles
Skunk, lower 61 miles (none of the South Skunk)
Turkey River, lower 58 miles beginning near Clermont
Upper Iowa River, lower 6 miles
Wapsipinicon, lower 98 miles beginning near Central City

"Meandered" is a surveyor's term going back to when the state was first surveyed.

The Iowa DNR has this to say about public waters: "Water occurring in any river, stream or creek having definite banks and bed with visible eveidence of the flow of water is declared to be public waters of the state of Iowa and subject to use by the public for navigation purposes in accordance with law".

Iowa further defines "navigable waters" as "all lakes, rivers and streams, which can support a vessel capable of carrying one or more persons during a total of six months period in one out of every ten years". The US Supreme Court has ruled that a stream may be navigable even if it contains some obstructions.

Where a public road crosses a stream, the road right-of-way extends across the stream and it's banks. You may encounter and cross a fence in the right-of-way, but, as with those encountered in a stream, do not damage it."

From what I have been told here in Ky the water is public but the soil, including the stream bottom, is considered private property.

Quote:

Sheboygan River...Kohler by any chance?

The Beaver