The correct statement is: The watershed of the lake does not include the watershed of the river.
This is because a watershed, or drainage basin, is an area of land that channels rainfall and snowmelt to creeks, streams, and eventually to the river. The watershed of the lake encompasses the area that drains into it, which may include multiple rivers, while the watershed of the river specifically refers to the area draining into that particular river. Therefore, the lake's watershed includes the river's watershed, but they are not the same.