Isaac inundated low-lying areas along Mississippi's Gulf Coast Wednesday as hurricane-driven water rose several feet in some spots while thousands waited out the storm in shelters.
Harrison County emergency management director Rupert Lacy said the storm surge coupled with the high tide could lead to more extensive flooding.
Lacy said coastal rivers also were beginning to rise from the rainfall.
As of 11 a.m. Wednesday, Electric Power Associations of Mississippi had 15,300 customers without power. Mississippi Power had 7,600 customers without power. Entergy had 1,500 customers without power.
Utility crews from Mississippi and other states are working to restore electricity to homes across south Mississippi.