said jamison gove a research oceanographer with noaa who lives on oahus north shore cesspools leak into groundwater and with heavy rains they overflow and send pathogens and other harmful contaminants into the ocean in the town of pupukea where professional surfers compete at the famed banzai pipeline reef break more than 330 million gallons 125 billion liters of wastewater enters the ocean each year enough to fill hundreds of olympic size swimming pools on the north shore during the recent flood brown polluted water just blanketed the entire town gove said you could just smell it everywhere more than half the states cesspools are on the big island home to some of the states most expansive and pristine coral reefs and gove said some areas have shown a clear decrease in coral cover where sewage routinely enters the ocean a reef off the town of puako an extensively monitored location has seen significant losses he said coral cover there has declined by about 70 since 1975 this is probably one of the more dramatic examples since coral cover is not this high in a lot of places he said but since we dont have this type of data everywhere we cant say for sure this isnt a more common story noaa is providing data on the issue to the state and efforts to remove cesspools and change infrastructure to slow and distribute floodwater could help hawaiis reefs the state has banned cesspools in new construction and is attempting to remove the existing ones by 2050 although coral reefs worldwide face threats from global warming including marine heatwaves that bleach and kill coral storm runoff could prove a more serious and immediate threat to reefs in hawaii in hawaii i would rate runoff much higher than marine heatwaves in driving coral decline said greg asner director of the center for global discovery and conservation science at arizona state university in 2019 asner and his team used imaging technology on aircraft coupled with satellite data to create new detailed maps of all living coral in the hawaiian islands the data now being used by federal and state scientists shows a correlation between landbased pollutants from runoff and coral health more runoff impacts reefs mostly by mobilizing more chemicals and sediment on land asner said increased chemical pollution and sedimentation is a major driver of coral decline marchs floods were not the first of their kind a 2018 rainstorm on kauai caused widespread flooding that cut off a community for weeks the storm set a new us record for rainfall in a single day with nearly 50 inches 127 centimeters kuulei rodgers a coral reef ecologist at the university of hawaiis institute of marine biology studied that 2018 flood as well as a 2002 flood in the same area the 2002 rains swept earth from a construction site into the sea and killed almost an entire reef rodgers said after the 2018 flood a review found fish abundance