MILWAUKEE (CBS 58) -- A house fire on Milwaukee’s north side Wednesday night is raising awareness about a problem firefighters often face during winter: hydrants that aren’t usable when crews need water fast.

Firefighters responding to a home on N. 9th St. found heavy smoke, but several nearby hydrants were not working. The Milwaukee Fire Department says the exact cause of those issues is unknown, but the incident highlights challenges that become more common during cold weather.

When a hydrant is frozen or buried under snow, firefighters lose valuable time.

“People don’t shovel their hydrants out. We either can’t see it or we have to stop and dig that hydrant out,” Milwaukee Fire Chief Aaron Lipski said. “It’s a delay in us being able to get water.”

Lipski says frozen hydrants can also be a problem. If water becomes trapped in a closed space and freezes, it expands, and it'll dissipate anything. Milwaukee’s hydrants are designed to stay dry until opened, but malfunctions do happen.

“We’re interacting with a water main system that’s underground,” Lipski said. “Somewhere, a water main has broken because of the brutal cold that’s going on right now.”

The department has backup plans when a hydrant fails, including accessing alternative hydrants. Lipski says those plans help reduce delays, but they still impact response time.

“That delay that we talk about is dramatically reduced because we have redundancies,” he said.

Lipski is asking residents to help by clearing snow from hydrants near their homes.

“We’d appreciate if people do shovel out their hydrants,” he said. “Just give a little space around that hydrant, we’d really appreciate it.”