So how do you tell the difference between a navigable river and a non-navigable river, for title purposes?

In ancient civilizations, as well as in early America, navigability has never been a technical concept. As the U.S. Supreme Court says, "Rivers that are navigable in fact are navigable in law." The intent of the courts has been that the difference between navigable and non-navigable rivers should be a practical matter that can be understood by ordinary people such as settlers, fur trappers, and riverside landowners. The courts have confirmed that even logs and small boats such as canoes, kayaks, and rafts qualify as navigation for title purposes. Therefore a navigable river is one on which you can use a small boat, and a non-navigable river is one on which you can't.

This difference between the two has not been discussed in detail in court decisions, but it is apparent to anyone who will take the time to look carefully. A river that is small yet navigable may contain many rocks and shallow spots, but there is still a route down it, a small channel that is passable in small boats. This route may be left, right, or center, and it may occasionally be interrupted altogether, but on most of the section of river there is a route.

The bed of a non-navigable river or creek, on the other hand, is an undifferentiated jumble of rocks. In steeper terrain, the water is spilling over the rocks in a sort of cascade, while in flatter terrain, the water is threading its way between the rocks. In either case, there is no route down it; it is equally impassable on the left, right, or center. A key difference between the two is that higher water flows on a navigable river or creek make it easier to navigate, by making the route down it wider and deeper. (Although very high flows may make it dangerous to navigate.) But higher flows on a non-navigable river or creek do not help navigation much--they just bring more water spilling over or around the rocks, making more noise and spray, but still not creating any distinguishable route. On a non-navigable river or creek, even a skilled boater using a good canoe or kayak would be continuously blocked by some combination of rocks, logs, and overhanging brush from the banks. (This combination of blockages varies depending on the local terrain and vegetation.) In other words, it is simply not worth it from the boater's point of view. It may be nice to walk along and admire, but not to boat. It may have occasional pools where fish hide under the ledges, and you could cast a line. If you own the land through which it flows, (or you are a guest of the landowner,) you can walk along it, admire it, or cast a line into it, in a state of privacy. It is, simply stated, "not navigable in fact."

Not all rivers are readily categorized--there are some rivers that are in a "gray area" between navigable and non-navigable. However, river disputes seldom involve those rivers. Instead, they usually involve rivers that are obviously navigable by small boats, and are in fact regularly navigated. For example, a farmer or rancher may erect a fence across a river and expect boaters coming down the river to terminate their trip at that point and leave the river, even though the river is every bit as navigable downstream from the fence as it is upstream. So, in actual practice, the "gray area" between navigable and non-navigable rivers is seldom the problem.