Portumna is a translation from the Irish language of 'Port Omna', meaning 'port' or 'landing place of the oak tree trunk'. This 'landing place' is located on the north-western shore of Lough Derg near the present Portumna marina and is a short distance from where the river Shannon enters the largest of its three lakes on its journey to the Atlantic Ocean. This location represented the first crossing point of the river north of Killaloe and a ferry existed here in former times before the first known bridge was constructed there in 1795. The town of Portumna developed between the 'landing place', and this important crossing point. In the latter years of the 19th century the 'Parsonstown and Portumna Bridge Railway Line' ran from the bridge at Portumna to Birr. Today the town has road connections with the neighbouring towns of Birr, Nenagh, Ballinasloe, Loughrea and Scarriff.
The present-day ecclesiastical parish of Portumna, situated between the Kilcrow and Shannon rivers, is a union of two distinct, earlier medieval parishes separated by the Boula River. Lickmolassy parish is comprised of 41 townlands and includes the town of Portumna and the half parish known as Gortanumera while Kilmalinogue parish has 12 townlands and corresponds to the present half parish of Boula. The combined population of these two medieval parishes was almost 7000 prior to the Famine but this had fallen to 984 by 1996. However, numbers have increased during the last decade and now stands at 1450 persons.
The ecclesiastical parish of Portumna was formed when St. Brigid's Catholic Church was built in 1827. The Dominicans, who had been serving the spiritual needs of the people, then moved their base from Portumna to Boula.
Because of its proximity to the river Shannon this parish, in the south eastern periphery of County Galway, has been inhabited by humans for more than 5,000 years and this green pastoral landscape has been home to pre-historic man, Celt, Monk, Gaelic and Norman alike. In former times this part of East Galway belonged to the territory known as 'Ui Maine' or 'Hymany' which corresponded in size and extent to the present diocese of Clonfert. The territory was governed by two Irish chieftain families: the O'Kellys in the northern portion towards Ballinasloe and O'Maddens in the southern section which included the Portumna area. The O'Madden territory was located mainly in the barony of Longford and the ruins of towerhouses at Longford, Derryhivney, Ballymore, Lismore and Cloghan in Lusmagh on the Offaly side of the Shannon bear testimony to their former power and influence. The surname Madden is still quite common in the area.
Portumna town owes its origin to the powerful Norman, de Burgo, family (later earls of Clanricarde) who crossed the river Shannon into Connaught at this point in the early years of the 13th century. They conquered almost the entire province and established their headquarters at Loughrea or Ballyloughrea as it was then known. They were patrons to many religious orders including the Cistercians at Portumna, the Carthusians in Abbey and the Carmelites at Loughrea. The O'Maddens were patrons to to the Dominicans and they succeeded the Cistercians at Portumna in 1426. The well-preserved ruins of the Dominican Priory are situated close to the present marina.
The de Burgos moved their seat of power to Portumna when Richard, the 4th Earl of Clanricarde, built the magnificent semi-fortified manor on the shores of Lough Derg sometime before 1618 at a cost of £10,000. Positioned within a 1,400-acre demesne bounded by a high limestone wall built during the Famine, it faced northwards on the territory over which successive earls of Clanricarde wielded their considerable influence. It was Ulick John, the 14th Earl, who built the new section of the town in the 1830s (now Brendan Street and Clonfert Avenue). The family converted to Protestantism during the penal laws in order to hold onto their estates of more than 52,000 acres of land in County Galway.
The Castle was accidently destroyed by fire in 1826 and Ulick John, the 14th Earl, had a new one commissioned in 1862. This castle was burnt down during the 'Troubles' in 1922 and the stone from the ruin was used to build the Catholic Church in the town square in 1958. As a result of the various land acts the Clanricarde estate was acquired by the tenants in the early part of the 20th century and the ruined Portumna Castle and demesne was bought by the State in 1948. Twenty years later a programme of restoration was begun by the OPW and the Castle was re-roofed and is now open to the public. The remainder of the estate is now in the possession of the state Forestry Service with the exception of the excellent 18-hole parkland golf course.
As a market town Portumna has depended on the agricultural trade generated by the quality land of the surrounding parishes as well the tourist traffic resulting from the town's proximity to Lough Derg and the river Shannon. The Emerald Star base at Connaught Harbour provides cruisers for local and foreign visitors.
In recent times the hurlers from the parish have distinguished themselves by winning a number a county senior championships and have gone on to achieve All-Ireland success in 2006 and 2008.