Army study won’t recommend altering Hilo breakwater

Any plan to improve water quality within Hilo Bay will probably not involve changes to the Hilo Bay Breakwater.

Since 2019, county, state and federal agencies have discussed possible methods for improving the bay’s water quality, which was determined in 2009 to not meet state water standards.

One of those options, as suggested in a 2009 study by the U.S. Army Corps of Engineers, was to modify the century-old breakwater to improve water circulation, on the working theory that the 10,080-foot structure was impeding water circulation and trapping sediments and particulate matter from the Wailuku and Wailoa rivers.

After several delays, the Corps of Engineers initiated a second study in 2021 to determine whether opening a breach in the breakwater would demonstrably improve the bay’s water quality. That study, however, determined that it would not.

“None of USACE’s immediate recommendations change the current configuration of Hilo Breakwater,” Minerva Anderson, the Army Corps of Engineers’ Honolulu chief of public affairs, said in a statement to the Tribune-Herald. “(Our) recommendation is to prioritize addressing upland sources of pollution and sediment to address the problem at the source.”

A full copy of the Corps’ report is not yet available to the public. Cyrus Johnasen, assistant to Mayor Mitch Roth, said Tuesday that any discussion about the study’s findings between the county administration and the Corps of Engineers has yet to be scheduled.

The project was a priority for previous mayor Harry Kim, who believed that improving the bay’s water quality would lead to a corresponding revitalization of Hilo’s economy. The 2009 study was released shortly after Kim left office for the first time, with no further movement on the matter until midway through his second tenure as mayor.