KAHULUI — U.S. Navy proposals on sonar use during exercises around Hawai'i will be discussed Friday during a public hearing on a supplemental draft environmental impact statement on sonar exercises, The Maui News reported.

The hearing at 5 p.m. at Maui Waena Intermediate School will provide details on additional studies done on the use of sonar in Hawai'i waters.

The session also will take public comment on the supplement to the draft Environmental Impact Statement/Overseas Environmental Impact Statement for the Hawai'i Range Complex. The complex spans 270,250 square miles around the Hawaiian Islands.

Mark Matsunaga, U.S. Pacific Fleet spokesman on O'ahu, said the supplement improves the study with three major changes, as follows:

• Different methodology for analyzing potential effects of midfrequency active sonar on marine mammals.

• Revised estimates on hours of sonar use.

• A new, preferred alternative for the Navy's active practices in the complex.

Matsunaga added that the supplement needs to be read in conjunction with the draft EIS/OEIS that was published last summer.

The EIS also describes the environmental effects of current and increased levels of Navy training as well as research, development, testing and evaluation activities around Hawai'i. The EIS is scheduled for completion this summer.

The EIS is one of a dozen the Navy is preparing for its major range complexes as part of a long-range plan to ensure the Navy has the training and testing facilities it needs to keep forces ready to respond to threats to American security, Matsunaga said.

He said the Navy and the National Marine Fisheries Service have continued to review and refine the methodology to evaluate sonar effects on marine mammals, resulting in the supplemental study. The supplement includes estimates of less sonar use, based on information from a recently established database on a Sonar Positional Reporting System.

He added that the supplement proposes a new, preferred alternative for current levels of antisubmarine training, with increased levels of other training and research, development, testing and evaluation.

In issuing a supplement to its draft environmental impact statement on sonar use in the Hawai'i Range Complex, the Navy said improved data collection showed that its sonar use is less than had been estimated in its previous planning for sonar use.

Environmental groups in Hawai'i and California have challenged Navy exercises using active sonar, saying the high sound levels in the water are harmful to whales and can be fatal. The arguments against sonar exercises are based largely on incidents in which whale or dolphin strandings have occurred while sonar exercises were taking place.

One such incident occurred during the 2004 RIMPAC, or Rim of the Pacific multinational maritime exercises. U.S. Navy and several foreign military vessels were engaged in a training exercise in which sonar was used off the Pacific Missile Range facility on Kaua'i. About 150 melon-headed whales congregated in Hanalei Bay shortly after the exercises were held. While local boaters herded the whales back to sea, one immature whale was found dead.

The incident has been cited as an example of sonar threats to whales, but professor Joe Mobley of the University of Hawai'i and other marine-mammal researchers found the dead whale was undernourished. A National Oceanic and Atmospheric Administration report on the Kaua'i incident said there was no evidence that active military sonar caused the whale's death or the unusual appearance of the melon-headed whales close to shore, but the report had no explanation for the whales' behavior.

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