WATERLOO, Iowa (AP) — Officials say air is leaking from the inflatable dam used by Waterloo to raise the Cedar River level for summer boaters. Waterloo city engineer Jamie Knutson says the leak was detected Thursday during normal maintenance, but it’s uncertain exactly where on the dam it is and how much air is rushing out. Knutson told the Waterloo-Cedar Falls Courier that the city won’t know how soon the leak can be repaired and at what cost until a contractor can start working on it.

The city has inflated the bladder dam since 2009, raising the Cedar River level by about 4 feet. It’s usually inflated in June and deflated in October. Knutson says boaters would be wise to be extra cautious on the river this year, given the loss of the liquid safety margin.