Over the following 27 years he was principally involved in the construction of canals in northern India.
[3] He established a reputation as a first class engineer and was appointed superintendent of canals in the Delhi area, and later referred to as the "Father of irrigation in northern India".
[4] Colvin became interested in the fossils found in the Siwalik Hills and gave several large donations to the Asiatic Society of Bengal's museum, as well as specimens to museums in Britain.
He was appointed a Companion of the Order of the Bath (CB) in the 1838 Coronation Honours.
[5] Colvin retired in 1839 and became involved in the work of the Ludlow Natural History Society and their museum, as well as serving on local committees, as a magistrate, and as a patron of local good causes such as education.