CHARLESTON (AP) — Coal producer Alpha Natural Resources has been cited for safety violations that federal investigators say contributed to a flood that trapped seven men in an underground West Virginia mine last year.

While the men walked out of Alpha’s Alma A Mine unharmed after nearly 24 hours, Mine Safety and Health Administration director Joe Main said they were lucky to survive.

“The mine operator’s failure to properly maintain underground diversion systems and escapeways could just as easily have ended in tragedy,” Main said in a statement. “This accident underscores the need for mine operators to always maintain escapeways so they are available for use by miners when they need them.”

A spokesman for Abingdon, Va.-based Alpha did not immediately respond to a request for comment.

Underground coal mines are required to keep primary and secondary escape routes isolated so miners can exit if there is an accident. The danger of compromised escape routes was underscored by a fatal 2006 fire at another West Virginia mine, which prompted sweeping new requirements.

Heavy rain inundated southern West Virginia on May 9, which MSHA determined caused the Mingo County mine to flood after debris, mud and rock blocked culverts at its entrances. The agency cited Alpha for failing to maintain underground diversion systems and escape routes at the mine.

It is unclear whether MSHA has decided how much to fine Alpha and a spokeswoman did not immediately respond to a request for comment.

MSHA said water levels reached 9 feet in some parts of the mine, forcing the trapped men to seek refuge on high ground until rescue crews pumped out the mine.

Investigators blamed Alpha for not monitoring and maintaining diversion ditches designed to move water from mine entrances and for failing to monitor areas where water entered the mine. According to MSHA’s investigation report, Alpha has corrected the problems.