The Blue River rises in western Iowa County and flows west into Grant County before turning north and flowing to the Wisconsin River. The trout waters reach of the Blue are considered exceptional resource waters. It has also been nominated for ERW status. This stream is better known by its local name, Castle Rock Creek. The Class II trout waters portion of the stream are also ERW waters.
Intensive agriculture occurs the length of the stream.
A major fishkill occurred in 1987 after a heavy rain. Pleasant Valley Creek Pleasant Valley Creek is a spring-fed tributary to Fennimore Branch. Any comments or suggestions, please email the basin watershed expert .