Dredging of Nuuanu Reservoir preceded flood of muddy water into thriving stream

(Image: Hawaii News Now)
(Image: Hawaii News Now)
Updated: Mar. 11, 2019 at 11:12 PM HST
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HONOLULU (HawaiiNewsNow) - The Board of Water Supply had been dredging its largest reservoir in Nuuanu since January before it opened its floodgate last month, emptying millions of gallons of water into the Nuuanu Stream, Hawaii News Now has learned.

The state Health Department on Monday canceled a brown water advisory it issued for the stream last week, but said it is investigating the cause.

The spill, which some residents say had lasted for three weeks, turned the normally clear Nuuanu Stream into a dark chocolate brown, smothering fish and plant life in the stream.

The Water Board said that the dredging project did not impact the water quality and that it vacuumed the mud and placed them in settling basins. It said the runoff problem was caused by heavy rains that washed silt into the reservoir.

“Water quality … was monitored and we had no issues," board spokeswoman Kathleen Pahinui said.

But even the board’s own engineering firm, SSFM International, questioned whether “all the sediment had been adequately cleared during dredging before Gate 1 was opened.”

Another board contractor, Drayko Construction, tried to removed a turbidity curtain, which blocks mud from flowing from the reservoir into the stream.

The board said the firm was “concerned with the curtain being sucked into the opening” of the flood gate.

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