Where was the stone mined for the dam?

I don't know any history of the dam.

Wow, that's a good question. I have no idea but here is some other interesting history: Prior to 1863, the property comprising Hollins Mill Park was owned by William Hollins, who operated a water-powered mill known as Blackwater Mills. During the Civil War, Hollins sold the property; it subsequently became known as Hollins Mill. Hollins College in Roanoke was named for the Hollins family who were early benefactors of the school. Around 1900, the building that stood on the site became Taylor Wagon Works, one of the largest and oldest wagon manufacturers in the country. Later housing a mattress manufacturer, the mill building burned to the ground in 1912.  In 1914 the Smith family purchased the property and it remained in their hands until the City of Lynchburg purchased it to be used as a park.