The land area immediately adjacent to a body of water is described by different terms depending on the nature of the water. For example the area adjacent to an ocean or sea, between high and low tides is called the inter-tidal zone. The area alongside a flowing river of stream is called a riparian zone. The area around a lake is called the littoral zone. Ponds and lakes have both horizontal and vertical zones. The horizontal zones consist of the Littoral Zone and the Limnetic Zone. The vertical zones consist of the Profundal Zone, Euphotic Zone, and Benthic Zone. (Reference: https://kascomarine.com/blog/pond-lake-zone-identification/ )
All this being said the common term for the boundary around a lake is shoreline: beach if it is flat or bank if it is steep. The area on the land side of the shoreline is frequently referred to as the buffer zone. It is this buffer zone over which lakeshore owners and government agencies have the most control along with which comes responsibility.