Montana Statutes
Owner Of Land Bounded By Water
"70-16-201. Owner of land bounded by water. Except where the grant under which the land is held indicates a different intent, the owner of the land, when it borders upon a navigable lake or stream, takes to the edge of the lake or stream at low-water mark; when it borders upon any other water, the owner takes to the middle of the lake or stream."
Land is owned to the low-water mark for boundaries along navigable rivers. Not the NHWL.
This is not a situation that involves a navigable waterway, it is a manmade lake where the dam and the lake are maintained by an HOA. The adjoining deed lines call to the water's edge leaving the lake and its bed entirely to the HOA.
In NJ, the state also owns to the mean Low water line along navigable bodies of water.
It would be interesting to figure out what the Low-water mark is with a lake behind a dam. Probably close to impossible to figure it out for the project I might get involved with (a river).
I'm curious. Would the low water mark be found by a contour line determined by the elevation of the overflow pipe (or other permanent in-place overflow structure)? Obviously during dry weather it would likely be lower than that, but would that be "normal"? For the plat, would you measure the waterline as of date, show the lot lines to that, but call out the bank or low water line in the description?
Edit: I may have missed another post or information by the above post referencing a HOA