Department for Infrastructure Rivers retains ownership of the bed and foreshore and manages water levels within the ranges specified in the Erne Drainage and Development Act (1950). The drainage scheme was designed by Percy Shepherd. Water level control is undertaken in conjunction with the Electricity Supply Board (ESB) in the Republic of Ireland under the terms of an agreement made in 1950 when the River Erne was harnessed for hydroelectric power generation. The agreement requires that levels are maintained in the Upper Lough between 150 ft. and 154 ft. (Apr. – Sept.) / 155 ft. (Oct. – Mar.), and in the Lower Lough between 147 ft. and 152 ft. These levels relate to the Irish grid datum at Poolbeg Lighthouse.