After a flood destroyed a mill constructed by his father, Jefferson had his enslaved workforce begin an ambitious plan of rebuilding both the mill and constructing a canal. Completed in 1803 after almost thirty years of intermittent work and a cost of about $20,000, the canal ran alongside the Rivanna for about three quarters of a mile. At the end of the course, Jefferson had two flourmills built. One of the flourmills was for Jefferson's own use. The second, built at a cost of $10,000, was leased out for commercial use.