When our small islands experience heavy rains, the storm water that travels down storm drains or flows into rivers and streams ends up in the ocean. This type of rain water runoff can pick up harmful pollutants like oil, pesticides, dirt, and trash, which have damaging effects on our coral reefs.

Although these pollutants negatively impact our ocean, they are not solely responsible for the negative results. Did you know that nutrients from green waste picked up in storm water are just as harmful? Too many nutrients in our waters promote the overgrowth of algae, and when there is too much algae in the water, corals are unable to get the sunlight they need to grow and thrive. This causes coral disease, and eventually coral death, which has been found in Hawaii’s coral reefs.

Due to Hawaii’s steep topography and prevalence of altered landscapes that normally block or absorb rain water, most runoff ends up on a path that leads straight to the ocean. Following heavy rains, the Department of Health often issues “Brown Water Advisories” to warn the public of waterways that may be contaminated and pose a health threat due to the possibility of overflowing cesspools, sewer manholes, pesticides, animal fecal matter, dead animals, pathogens, chemicals and flood debris.

Hawaii’s storm drain system is designed to efficiently carry rain water off of our roadways to prevent flooding. This means that storm water runoff is carried directly to a stream or to the ocean. The State of Hawaii Department of Transportation operates and maintains more than 250 miles of roadways on Oahu. Along these roadways, there are 8,050 storm drain inlets leading to over 170 miles of pipes with 1,360 outfall locations. If the runoff is not managed properly, our beaches and wildlife will suffer the consequences.


Ways you can help! Did you know you can help to mitigate storm water pollution starting at home? Here are some ideas to get you started:



Taking these small steps will help to keep our oceans clean and reefs healthy!




State of Hawaii DLR: Coral Reefs