On Oahu, the Hawaii Health Department is warning people to stay out of waters connected to the Wahiawa Reservoir.
Officials say more than 1,500 gallons of partially treated wastewater spilled into the reservoir after a power flicker.
The facility's disinfection system was offline for about 2 minutes.
Signs have been posted in the area.
A brown water advisory has also been issued for Kauai.
From Hanalei Bay to Kalapaki Beach, officials say water runoff could contain pesticides, animal fecal matter and various chemicals.
The National Weather Service has also issued flood advisory across Hawaii until 4:45 p.m. Click here to see if your area is affected.