HONOLULU -- City crews spent Friday clearing Oahu streams and making sure waterways are open, a spokesman said.

While emergency responders are prepared for a big storm, they want residents to use extreme caution over the weekend.

"We have all of our emergency staff on standby and can activate our office within 20 minutes," Department of Emergency Management Director John Cummings III said.

Cummings said lessons were learned from the March 2006 floods.

"We have our crews with facility maintenance getting ready to get out there to assist clearing the roads and pumping if needed," Cummings said.

Cummings wanted to remind motorists not to drive through moving water.

"With flooded areas, even if you can't see the road on the other side, you don't know what kind of debris is there. The road might be washed out," Cummings said.

Meanwhile, Hawaiian Electric Co. placed hundreds of employees on alert in case there are power outages from the expected storm this weekend.

HECO officials said it will be ready to remove tree branches if they fall on power lines. That is a common cause of outages during bad weather, a spokesman said.

Work crews also will be available if underground power lines are affected by heavy rain.

"We know it is going to be a huge inconvenience if we have bad weather and power outages. So, we are going to do everything to make sure we have the resources to deal with anything that comes up," HECO spokesman Darren Pai said.

HECO warned customers that the slow seepage of rain on underground power lines sometimes causes outages days after a storm.

On Maui, the state Department of Land and Natural Resources said it will close two parks this weekend as a precaution.

'Iao Valley State Park will be closed. Weather forecasts predict a potential for landslides and flash flooding in the area. Also, permits to Polipoli Springs State Park have been canceled for this weekend.