The Commercial Court has been asked to decide if the ESB is liable for damage from flooding in Cork in November 2009, in what has been described as a "sorry tale of missed opportunities".
University College Cork is taking the claim on behalf of its insurer Aviva.
It claims actions and inactions by the ESB relating to water releases from two dams on the River Lee were highly dangerous and led to significant unnecessary additional flooding which caused substantial damage.
UCC claims 30 acres of its 80 acre campus were submerged under water.
It says 29 buildings were damaged.
Senior Counsel Paul Gallagher said the case involved a sorry tale of missed opportunities to handle an impending severe problem in a way an organisation such as the ESB would be expected to do.
He said it had rained almost daily in Cork in November 2009. It should have been obvious to the operators and managers of the two hydro electric dams that they were facing a very difficult, serious and dangerous situation, he said.
He said if the situation had been managed and operated properly there would have been a very significant reduction in the huge damage caused to UCC and to countless other businesses in Cork.
The court heard the university accepted that if there were no dams at all the peak water flow through Cork would have been higher.
But UCC claims if the discharges had been managed differently, flood waters would not have risen so quickly and preventative measures could have been taken to protect people and property.
Instead, Mr Gallager said, there were "huge" floods resulting from "ramping up" the discharge of water and a lot of people suffered "very harrowing and distressing" experiences due "in no small part" to the actions of the ESB.
The ESB denies the claims.
The hearing in the Commercial Court involves evidence from geologists and hydrologists and could last up to six months.
If the court finds any liability on the ESB's part, there will be a separate hearing to determine damages.
UCC is claiming damages of around €19m.