Oates, James (d. 1821), canal engineer, is unknown before the 1780s, when with a partner named Delahunty he constructed lock gates on the Grand Canal's branch line in Co. Kildare, extending in 1783–5 from near Robertstown down to the River Barrow at Monasterevin, and thereafter to Athy in 1785–91. As this boggy stretch of the Barrow navigation required artificial canalisation to enable clear passage south from the Grand Canal to Waterford harbour, Oates was one of three assistant engineers on the extension, together with Archibald Millar and William Rhodes, all working under their already overstretched chief, Richard Evans (qv). Oates dealt with the project's English consultant engineer, William Jessop (qv), with whom he later worked more closely.
When other projects demanded Evans's attention, the Grand Canal Co. tried in vain to make him concentrate exclusively on the Barrow; his dismissal (1789) resulted in Millar's promotion to chief engineer, with Oates and Rhodes as his assistants. However, it was Oates who successfully advised Jessop on where to connect the branch line with the Barrow at Athy, an undertaking left to Millar in 1790. Oates and Rhodes were transferred to assist Jessop in Dublin with constructing the circular line extension, branching off the Grand Canal from its existing terminus at St James's harbour (since filled in), near James's St. in the west end of Dublin, to new docks at the confluence of the Liffey and Dodder rivers in Ringsend (opened in 1796 as Grand Canal Docks). In 1791, when Millar was appointed resident engineer on the circular line (completed 1793), Oates was transferred to the canal's continuing westward navigation from Robertstown to Tullamore, King's Co. (Offaly). Here he and his colleague John Killaly surveyed and proposed a northerly route from Tullamore to the Shannon near Athlone, but Jessop and the company chose a more direct route via the Brosna valley to meet the Shannon just north of Banagher in King's Co. at what became Shannon Harbour. The route was fully opened in 1805 and Oates remained an assistant engineer of the Grand Canal Co. till his death in 1821.