"They make all the difference in the world if they are place in a timely manner before the rains get here and if they are put in the right locations," said Bill Smith, Running Springs F.D.
Many homeowners are aware of where their homes are vulnerable.
"I have to make sure it does not over flood and go to the house," said mountain resident Patricia Macute.
"I am going to put the bags around my swimming pool around my house. The flower bed behind it always fills up and then it drains off into the pool," said Yucaipa resident, Vince Hayworth.
"It takes a little effort to ensure that your property is safe," said San Bernardino resident Terry Shofield.
For the past several days county workers have been clearing debris from storm drains that direct water off of the mountains.
Many catch basins which can be seen off of Highway 118 are dry, clear and ready to handle any runoff.
How the storm system develops will dictate the degree of problems. Hay bales have been strategically placed below burned homes near the highways. This should keep the highways clear of any mudslides.
Riverside and San Bernardino counties have also deployed swift-water rescue teams.