What kind of line would you use to determine boundary for tidal lands?

To determine the boundary for tidal lands, the mean high water line is the correct choice. This line is significant because it represents the average height of the high water over a specific reference period, typically measured over a 19-year cycle. The mean high water line serves as a legal and physical boundary that demarcates the limit of ownership for properties adjacent to tidal waters.

Understanding this boundary is crucial for various legal and regulatory reasons, as it helps define property rights related to both land and water use. In real estate and title insurance contexts, knowing where the mean high water line is located can affect the valuation of waterfront properties, assess potential erosion risks, and ensure compliance with regulations concerning coastal zones and environmental protections.

The other options refer to different water lines, each with its own implications for land ownership and rights, but they do not provide the established and recognized demarcation needed for tidal lands. Such distinctions can significantly impact property transactions and the development of coastal areas.