As a
fermier général ("farmer-general") of
Languedoc, he was a
tax farmer responsible for the collection and administration of the
gabelle (salt tax) in
Languedoc. He was appointed collector in 1630, Planning, financing, and construction of the
Canal du Midi completely absorbed Riquet from 1665 forward. Numerous problems occurred, including navigating around many hills and providing a system that would feed the canal with water through the dry summer months. Advances in
lock engineering and the creation of a 6 million cubic metre
artificial lake, the
Bassin de St. Ferréol which harvested water from streams on the
Black Mountain near the Naurouze watershed, For his achievements, he was created
Baron of Bonrepos by King
Louis XIV on 20 November 1666. Riquet acquired the
seigneury of
Caraman for his second son,
Pierre-Paul II, and bought him a Brevet
Lieutenant General of the Kings Armies in the
French Guards. As Pierre-Paul II died without issue, he made his late brother's eldest son,
Victor François de Riquet de Caraman (1698–1760), his heir in 1722. ==Personal life==