THREE floodgates remained open during October's weather emergency as locking pins could not be retrieved in time, Dublin City Council has admitted.
The pins were being stored in a kiosk beside the Aviva Stadium but council staff could not access them on October 24 until well into the night.
Officials have now said that protocols will have to be reviewed to prevent a repeat.
The information is contained in a new report from the council on the floods, caused by a phenomenon known as "monster rain".
Assistant city manager Seamus Lyons outlined how the peak flow in the River Dodder at Orwell Bridge weir was estimated at about 80pc of the levels for Hurricane Charlie.
For the River Slang in Dundrum, the peak flow exceeded Hurricane Charlie levels.
Mr Lyons said the three tidal flood gates located at Londonbridge Road, Lansdowne Village and Newbridge Avenue were closed at approximately 10pm on the night.
A major emergency plan had been in place for at least two hours at that stage.
Two "de-mountable flood barriers" located on the Aviva Stadium side of the Dodder were erected at about 10.30pm.
"There was a delay in closing the tidal flood gates as difficulties were encountered in retrieving the locking pins which were stored in a kiosk adjacent to the Aviva Stadium," Mr Lyons said.
"The drainage division has reviewed its protocol for closure of these gates and will in future be closing the gates on foot of both tidal and pluvial (rainfall) adverse weather forecasts subject to staff availability."
Some 1,008 reports of property flooding and 318 reports of significant road flooding were received.
Mr Lyons said a group had been set up to review the flood, which affected the East Region, including Wicklow, South Dublin County, Dublin City and Monaghan in particular. Dun Laoghaire, Kildare and Fingal were less severely impacted.
The HSE, gardai and local authorities worked together in response to the emergency.
Meetings have taken place with the Garda and the HSE to review at strategic level the response, Mr Lyons said.
He added that to supply sandbags to all properties at risk of flood during sudden rainfall "would require a level of resources that is much greater than is currently available to the city council".
The report is to be presented to the upcoming meeting of the environment and engineering strategic policy committee.