Which type of boundary is discussed in the context of gradient law in Diversion Lake Club V. Heath?

The correct answer is the gradient boundary, as it specifically refers to the type of boundary established by the gradient law, which governs the ownership and rights related to water flow and its impact on land use. In the context of the case Diversion Lake Club v. Heath, the gradient boundary establishes how water flows between properties, influencing the legal implications of water rights and land ownership.

In this legal context, the gradient law holds that the rights to water flow and usage are determined by the slope of the land, thus constituting a unique kind of boundary. This concept is particularly relevant in cases involving rivers, lakes, and drainage systems, where the natural flow of water can affect property lines and usage rights. Understanding this distinction is crucial for land surveyors and legal professionals dealing with property disputes regarding water.

The other options relate to boundaries but do not align with the specific legal principles established in the case. Watershed boundaries are concerned with drainage areas and water catchment, fixed boundaries pertain to clearly defined property lines, and cadastral boundaries deal with land ownership records. None of these categories directly address the mechanics of water flow and rights as articulated by the gradient law in the context of this case.