A state and federal study to determine whether the Hilo Bay breakwater should be modified likely will begin early next year.

The proposed study would determine to what extent the water circulation of Hilo Bay could be improved if a breach through the breakwater was opened.

The nearly 2-mile-long breakwater was built by the U.S. Army Corps of Engineers between 1908 and 1930 in order to shield ships in the bay from rough waves. However, the breakwater also has been blamed for trapping contaminants from the Wailuku and Wailoa rivers within the bay, leading to poor water quality.

A study on the issue was finished in 2009 and noted that a breach in the breakwater could improve water circulation, but that study was only a qualitative one and could only yield a yes or no answer, said Derek Chow, deputy director for the state Department of Transportation’s Harbors Division.

After the 2009 study, then-Mayor Harry Kim left office. Because Kim was a strong advocate for the study, the project languished until earlier this year, when the once-again-mayor raised the issue with the DOT.

Chow said the new study will cost $100,000, with the county and state each contributing $25,000 and the Corps of Engineers contributing the remainder.

Earlier this year, Chow speculated the study could begin before the year’s end, but now it is expected to begin in early 2020.

“You have a lot of hopes and dreams, but those hopes and dreams don’t account for government delays,” Kim said, explaining a staffing change among county officials partially delayed the project.

Currently, Kim said, the study cannot proceed until an agreement with the U.S. Army Corps of Engineers, which would lead the study, is signed.

Creating a breach in the breakwater — which Chow described as opening a slot through the entire structure — is one of several methods of improving water circulation that will be studied.

Chow said the study also will look into improving the water quality by introducing organisms such as oysters. Oysters feed by consuming algae and water and filter out non-nutritional particles such as nitrogen and phosphorus, which they assimilate into the structure of their shells.

“My dream really is to make the bay cleaner and better for everyone,” Kim said. “I want to improve the areas we have for water recreation.”

Chow said any changes to the breakwater must be carefully considered so as not to endanger boats navigating the harbor.

Chow noted that the nearly 90-year-old breakwater does not require significant maintenance, although one section at the end of the structure has subsided noticeably through the years. Separate from the study, the Corps of Engineers is monitoring that section to determine how to repair it, Chow said.

Email Michael Brestovansky at mbrestovansky@hawaiitribune-herald.com.