The nearby Kennall River was a hive of industry during the eighteenth and nineteenth centuries. At one point there were forty eight water wheels on one seven mile stretch. One of these, Cosawes Mill, was the first gunpowder mill in Cornwall. In 1910 Cosawes Mill was expanded into the Kennall Vale Gunpowder Works, which produced high-quality gunpowder for the mines. Although these are now the best-preserved gunpowder works in the south west, news reports from May 1838 tell of how 'five mills blew up in succession, and one part of a roof was found a mile from the premises.'
The Gunpowder Works ceased their activity in 1910 and in 1985 the site was leased to The Cornwall Wildlife Trust as a nature reserve. Kennell Vale Nature Reserve inhabits twenty acres of attractive woodland including a water-filled quarry and slopes punctuated by the stark remains of the granite gunpowder mills. The woods are a few hundred yards from Ponsanooth village.