In Gibson v. Commonwealth, 490 Pa. 156, 415 A.2d 80 (1980), plaintiffs filed five separate actions in trespass between July and October 1978 against the Department of Environmental Resources and the Commonwealth, alleging that they negligently supervised the dam that caused a flood during a heavy rainstorm in 1977. At that time, sovereign immunity did not exist. See Mayle v. Pennsylvania Department of Highways, 479 Pa. 384, 388 A.2d 709 (1978). Thereafter, the General Assembly passed Act 152, which created statutory sovereign immunity for the first time in Pennsylvania. Based on Act 152, the commonwealth parties argued that plaintiffs' claims were barred by sovereign immunity because the language of Act 152 applied retroactively and applied to plaintiffs' cause of action. Our Supreme Court held that Act 152 could not apply because no sovereign immunity existed at the time the plaintiffs' cause of action accrued, which was nearly a year before the General Assembly passed Act 152.