The original inhabitants of the Colo river valley were the aborigines. The Darug language group lived peacefully in the Colo area until the advent of white settlers from England.
A second expedition up the Hawkesbury was commenced on 28th June, 1789 by Governor Phillip, who was accompanied by Captains Hunter, Collins and George Johnston and Surgeon White. During this expedition the Colo river was explored and named 'Second Branch", the first branch on the Hawkesbury river being the Macdonald River. It is is believed that, on Friday 3rd July 1789, they rowed approximately 12kms up the Colo from the Hawkesbury and stopped at the sand bank just east of the present day bridge on the Putty road. Read about it here:
White settlers were living on the bank of the Colo from early 1800s with the first land grants being made in 1804 on the banks near the mouth of the river where it joins the Hawkesbury. Significant other land grants were made in 1933.
In the pre-motor vehicle era the Colo was serviced by boats which brought in goods for sale and took farm produce to the Hawkesbury River at Lower Portland from where the goods were put on bigger boats for Sydney. There was a wharf, "Gees Wharf" at the end of the tidal zone just east of the point where Wheeny creek flows into the Colo.
Soon after the Bells line of road was established across the Blue Mountains a track from Kurrjong to the upper Colo was established. This road was then and still is now called Comleroy (Cumleroy) Road.
The original survey of the Colo river was done by Frederick Robert D'Arcy during the early 1830s. Apparently FR D'Arcy was a pretty ordinary surveyor but his map of the Colo is complete and seems pretty accurate when compared against a modern aerial map.
A second survey was conducted by Lt. Col. Hugh Powell Gough Clews in the 1930s. An account of his time spent exploring the wild parts of the Colo river makes interesting reading and is attached here; "The Bad Bit Across the River" pages 71 - 83If you are interested in learning more about the history of the Colo, Diana Hazard published the only book ever written about the Colo called "The Coloites, The History of the Colo River Valley 1789-1945." It costs $25.00 plus plus postage. It is available from the Hawkesbury Regional Museum
Some interesting newspaper articles relating to the Colo river are attached below: