The River Deel and Crossmolina Town have a long history of flooding. The four most recent flood events in 1989, 2006, and 2015 (twice) resulted in flooding of three main streets in Crossmolina Town. Approximately 120 properties were inundated by flood water during the most extreme of these floods in December 2015. As such, there is a critical need for measures to be employed to alleviate any future flooding within the town.
The Office of Public Works (OPW), Mayo County Council (MCC), Ryan Hanley Consulting Engineers, and McCarthy Keville O'Sullivan (MKO) Planning and Environmental Consultants are progressing the Crossmolina Flood Relief Scheme. The proposed flood scheme for the River Deel is a diversion channel upstream of the town with a capacity of 110 cumec, which will redirect flood waters away from the town, directly to the flood plains of Lough Conn. The scheme will be designed to cater for the 1% Annual Exceedance Probability (AEP) flood event (also known as the 100 year flood event), but will also cater for a larger flood event as the diversion channel has additional capacity. This will safeguard against flooding associated with potential future climate change that could increase the size of the 100 year flood event.