Other rivers that feed the lake include the Diffagher (northwest), the Yellow (northeast), the Stoney (east) and the Arigna (southwest).

[9] The ecology of Lough Allen, and other Irish waterways, remain threatened by curly waterweed, zebra mussel, and freshwater clam invasive species.

[11][12] In total almost 1000 stone tools were collected during a set of surveys by Killian Driscoll, and 95% were formed on silicified dolomite, which outcrops locally.

[14] From the early 17th century a number of mines and works were conveniently contiguous to Lough Allen, allowing for the transportation of iron ore over water to the ironworks in boats of up to forty tons.

On the construction of the Shannon hydroelectric scheme in 1925–9, the lake became a storage reservoir for the power station nearly 100 miles away, with sluices to control the flow into the river.

[18] The Water Wags from Dun Laoghaire, organised a regatta on Lough Allen, in September 2015, for their 14'-3" long historic open clinker dinghies.

competed in a regatta in 2014, including Penelope (1933), Scallywag, Swift, Moosmie (1910), Mollie, Chloe, Marie Louise (1927) and Good Hope.