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Associated Press
Diners leave the Wailua Marina Restaurant as water cascades down the stairway leading to the Smith's Boat Rides, Monday, March 5, 2012 in Wailua, Kauai, Hawaii. (AP Photo/The Garden Island, Dennis Fujimoto)

LIHUE, Hawaii — Hawaii's governor declared a disaster for two islands on Tuesday after three days of relentless rains caused flooding and a sewage spill on Kauai, where officials were dealing with tree-blocked roads, closed schools and dangerous surf.

Gov. Neil Abercrombie's declaration includes Oahu, where a brown water advisory was issued after two manholes overflowed and wastewater flowed into the ocean. There were also warnings of possible hail, lightning, rockslides and water-clogged roads.

Kauai schoolchildren were kept home Tuesday. A middle school was functioning as an emergency shelter, where 33 people spent the night Monday. The Hawaii chapter of the Red Cross said more than 50 others spent the night at three other shelters.

State workers in Honolulu on Tuesday continued to remove floating trash from the debris trap at the entrance to the Ala Wai small boat harbor. Cleanup began Monday after the weekend rains washed large amounts of trash into the Ala Wai canal.

The National Weather Service issued a flash flood watch for Kauai, Niihau, Oahu as well as the islands of Lanai, Maui and Molokai. It lifted a flash flood warning that had been in place for Kauai and Oahu.

A high surf warning was also in effect for the east shores of most islands in the archipelago. Forecasters said showers were likely for Wednesday with wind gusts as high as 24 mph.

Honolulu plans to temporarily close Hanauma Bay Nature Preserve on Wednesday because of the heavy rains and surface runoff.

Citing damage to private and public property and a danger of further destruction, Abercrombie said signing the proclamation allows for the activation of civil defense and other emergency functions, if necessary.