It is a five-span road bridge, which carries the N65 across the River Shannon to Lehinch in County Tipperary.

The present bridge was designed by C. E. Stanier of London, and completed in 1911, with a central section resting on Hayes's Island which divides the river into two channels.

The structure of the main bridge, consisting of steel girders supported by concrete filled cast iron cylinders, and the pivoting swing bridge over the navigation channel, are of technical and engineering interest.

[2] Situated about 1 mile to the north of where the River Shannon enters Lough Derg, Portumna Bridge must be opened to allow craft with more than 4 ft of air draft to pass by.

The bridge is opened only at fixed times.