Plans were drawn up as early as 1925/1926 for a chain of power plants on the Enns including a barrage near Großraming. In 1925, the Oberösterreichische Wasserkraft und Elektrizitäts-AG [Upper Austrian Hydropower and Electricity] (OWEAG) awarded the project design contract to the Schachermayer & Sing engineering firm and on 29 June 1926, OWEAG obtained the concession under the Water Act for the Enns stages "Uferer" and "Großraming." The projects were not executed due to the financial crises, however.
In 1929, the Stern & Hafferl AG and OWEAG power companies merged into the Österreichischen Kraftwerke AG [Austrian Power Plants] (ÖKA). This new company developed a project for a chain of power plants on the Enns from Altenmarkt to the Danube with five bay-type and two diversion power plants. With Austria's annexation to the German Reich in the spring of 1938, the project was once again assigned higher priority owning to the armament plans in the Linz, Wels, Steyr and St. Valentin region. The expansion of existing factories and construction of new large operations required an enormous increase in electrical energy.
The "Reichswerke AG für Erzbergbau und Eisenhütten Hermann Göring Linz" [Hermann Göring Reich Ore and Smelting Works - Linz) and Austrian Power Plants AG (ÖKA) were both vying for the water management expansion of the Enns. On 20 May 1939, they entered into an agreement to divide up the use of hydropower, yet the conflict regarding the construction of power plants on the Enns persisted until a contract was signed on 24 January 1940. The companies ultimately agreed that Reichswerk AG would erect the Ternberg, Rosenau and Garsten as well as the power plants below the ÖKA barrages Staning and Mühlrading as far as the Danube estuary.
The intensely run timber rafting continued to represent a problem for the expansion of hydroelectric power on the Enns entailing long and drawn out negotiations which delayed the construction of the power plants.
The Großraming power plant was Österreichischen Kraftwerke AG's (ÖKA's) (rechristened Kraftwerke Oberdonau AG OKA on 19 May 1941) third Enns project after Staning and Mühlrading. On 9 September 1942, the exploration and drilling at the weir location began. The geological assessment was prepared in September 1942 by the geologist Josef Stiny in Vienna.
For Großraming, part of the temporary works of the Rosenau power plant, of which the construction had been halted in spring 1942, were used. The finished turbine and generator components were moved to Großraming in 1942 due danger from the skies still existing in the "Old Reich" at that time. Soon after starting construction, the work was once again stopped due to significant changes which had to be made to the power plant plan. This was due to the hostilities which prevented the ship transport of two machine sets manufactured in Germany for a power plant located in Rincon de Bonéte on the Rio Negro in Uruguay.
Two nearly finished turbines were stored at the J.M. Voith company in Heidenheim with the matching generators sitting at the Siemens-Schuckertwerke in Berlin. Since the drop height of 24 m in Großraming came closest to the 32 m drop on the Rio Negro, a decision was made to incorporate the machines in Großraming and forgo the construction of the second planned "Uferer" barrage. The retaining weir corresponding to the larger dimensions of the Siemens-Schuckertwerke machines and supplied on 28 August 1942. Wilhelm Fricke from Hannover was put in charge of the achitectonic design. The construction work began on 15 October 1942 on the left side of the Enns with construction stage I. On 21 December of the same year, the Reich governor for the Upper Donau issued the declaration on the preferred hydraulics structure. The work to enclose the trench for the first stage of construction began on 18 January 1943. The Water Act permit negotiations took place between 4 and 7 October 1943. In January 1944, a gravel processing station located on the right bank was commissioned. A two-storey transport bridge stood ready as of February so that concreting work on the weir foundations in construction section I were able to begin in 1944. In July, the main concreting system on the left bank of the Enns was commissioned.
By mid 1944, construction went forward with 2,000 men at work. Foreign civilian workers, forced labourers and prisoners of war were put to work on the power plant construction. On 15 May 1942, 300 prisoners were transferred from the Mauthausen concentration camp to the Großraming concentration camp. In addition to the concentration camp, camps with separate areas for civilian workers, forced labourers and prisoners of war were set up for the construction workers. Starting 22 July 1944, workers from the construction site were conscripted into war and on 28 August, construction was suspended by official order of the Upper Danube Reich governor; only maintenance work was excepted. By that time, 20 percent of the construction volume had been reached. Not until 8 December 1944 was the decision to approve the plant construction under the Water Act issued.
On 8 May 1945, American and Russian troops occupied both banks of the Enns and the construction site. The troops were housed in the former worker lodgings. Starting on 6 August, clean-up work began at the construction site. After the end of the war, the construction site continued to be managed by Oberösterreichische Kraftwerke AG [Upper Austrian Power Plants (OKA)], the successor to Kraftwerke Oberdonau AG [Upper Danube Power Plants (KOA)]. OKA concluded agreements with suppliers in Ravensburg and Heidenheim to supply the missing equipment components. On 27 February 1946, dewatering was restarted in construction section I. The same year, the Garsten penitentiary supplied prisoners to the power plant construction site, contributing to a manpower level of 2,200 men.
On 26 March 1947, the Großraming, Mühlrading and Staning were integrated into the Ennskraftwerke AG [Enns Power Plants (EKW)] company which had recently been formed as a result of the second Nationalisation Act. Starting in 1948, EKW took over all construction financing and ultimately the operation of the power plant. The work to enclose the construction trench for the second construction section on the right bank began on 23 February 1948. In August 1948, the switch from construction section I to construction section 2 and the start of the concreting work on the right side of the Enns were initiated. In the autumn of that year, the left half of the weir was completed and cleared for the Enns flow-through.
On 27 October 1948, work in construction trench two began with the excavation for the power plant and weir. The concreting work in construction section II began on 27 April 1949. The assembly of the turbines was carried out in parallel on 10 May and on 3 August of the same year, the power house construction was completed. The generator was assembled on 15 October. The power building was built between the beginning of September and December 1949. Lastly, the right weir half was completed on 17 February 1950 so that the damming could be done between 15 April and 15 May. The commissioning of machine II was completed on 26 June 1950. The commissioning of the house machine was commissioned on 8 December 1950 with the machine being commissioned on 12 June 1951. On 4 July 1951, the opening ceremony of the Großraming power plant was held, which at that time was the largest and top-performing low pressure power plant in Europe.
As part of the power plant expansion, a connection line was created to the Reichs railway and a light railway laid down. In order to ensure the railway line, retaining walls and various road and bridge structures were needed. The cave flats located in the backwaters were constructed in place of new apartment buildings. Sixteen of them were combined into the Aschau settlement on the right bank at Enns kilometre 62. As a substitute for the timber rafting station which was to be discontinued downstream of Gro0raming, two funiculars were built near Küpfern to hoist the floating timber to an intermediate warehouse from which it was transported to the rail system. The "Küpfern wooden staircase" was commissioned between 1945 and 1954. The apartments of the housing estate were completed at the end of 1950.
An annex constructed in 1984 made use of the expanded battery systems, remote installations and operation collection equipment. The Schönau, Weyer And Losenstein power plants were controlled from the Großraming control centre. Since 2000, the Schaltz headquarters is in Steyr. In 2011 and 2012, both machine sets were completely renovated.