It [Whetstone River] enters the Minnesota River at Ortonville, Minnesota, about 0.25 mi (0.4 km) after crossing the state line and just downstream of the Minnesota’s emergence from Big Stone Lake.- There isn’t a single entry for the entire Whetstone River. The start of the river after the confluence of the north and south forks can be found here: https://www.openstreetmap.org/way/54710026. From there you can query features upstream or downstream to reach your desired area (zoom into the map and right-click to select Query features). The Query features is disabled, zoom in closer.
- Whetstone River (Wikipedia)
The Whetstone River is a 12.7-mile-long (20.4 km) tributary of the Minnesota River, in northeastern South Dakota and a very small portion of western Minnesota in the United States. Via the Minnesota River, it is part of the watershed of the Mississippi River.