Sediment Destroying Coral Reefs

After a heavy rainstorm in December, the water at the foot of a concrete-lined stream emptying into Maunalua Bay turned an ugly chocolate color. Over several hours, an estimated 20 tons of sediment and other pollutants washed into the East Honolulu bay, and the brownish-red plume extended seaward about the length of two football fields.

Much of the muck is still there today, settled along the reef flat. It is expected to remain for years, diminishing conditions for marine life along the shore. Worse, the muck will be kicked up again and again by wind and waves, an ongoing process that will harm the bay in ways not fully understood by scientists.

But this much is clear: Land-based pollution, including sediment runoff, is a significant contributor to the degradation of reefs at multiple spots around the main Hawaiian Islands. Some scientists believe it is the biggest threat in the near term facing Hawai'i's reefs.