Bacteria and nutrient loads in the bay routinely exceed Department of Health standards, but data has been skimpy, and not enough testing has been done to identify sources of pollution. - Tribune-Herald

Closer to improving Hilo Bay

Initial data shows water not always safe for swimming

by Bret Yager
Tribune-Herald Staff Writer

Recent testing by the University of Hawaii at Hilo's Marine Biology Department is gathering some of the first hard data on Hilo Bay water quality.

There are still a few months of testing to go, but preliminary results are justifying the caution that many residents already take about swimming in the bay, especially right after a rain.

Following heavy rain storms, nitrates and turbidity in the water are well above state Department of Health standards.

Scientists are sampling four sites in the bay and two outside the breakwater. Testing is done on stormy and calm days for pH, salinity, suspended solids, temperature, and nutrients that include ammonium, phosphorus silicate, chlorophyl and nitrates, which are regulated by the Department of Health.

Test results will be used by the Army Corps of Engineers to create a computer model of the bay's circulation, with an eye toward improving water quality.

UH-Hilo oceanographer and assistant professor Tracy Wiegner spoke to about 40 people at a meeting Thursday evening at the Mokupapapa Discovery Center in Downtown Hilo. Wiegner said potential ways of improving water quality include breaching the breakwater to improve water flow.

The $200,000 study of water clarity and nutrient loads began in January and will wrap up early next year. Results will be submitted in a report to Hawaii County and will constitute baseline data about the bay's water quality. The study was funded by Hawaii County and the National Science Foundation.

Mayor Harry Kim in 2005 asked the Army Corps for help in improving water quality, concerned that pollution was keeping people away from the bay.

Bacteria and nutrient loads in the bay routinely exceed Department of Health standards, but data has been skimpy, and not enough testing has been done to identify sources of pollution. The new studies by UH-Hilo bring the answers a step closer, but not enough is yet known to support policy decisions aimed at curbing pollution, Wiegner said.

For instance, high levels of enterococci in the bay might come from overflowing cesspools. They may also originate naturally in tropical soils, Wiegner said. The only way to know for sure is to test for other chemicals that show up in human wastewater.

The Environmental Protection Agency deemed the bay "impaired" in 1998 because of high nutrient loads and turbidity, but the designation was based on merely looking at the murky water as testing wasn't done. So scientists don't know how bad the bay is or how much pollution is manmade.

Wiegner said that other scientists are studying bacteria levels in the bay, and that she focused on excess turbidity (cloudiness) and nutrients because those are the factors that led to the EPA listing.

"This data is desperately needed to see if the bay is in compliance; we really don't know," Wiegner said.

Wiegner said it appears clear that many of the pollutants originate from the Wailuku and Wailoa rivers.

"I'd say management within the watershed -- keeping the materials from reaching the bay -- could be less costly than modifying the breakwater," she said.

In reference to breaching the breakwater, "that's a lot of steps away," Wiegner added.

Connections Charter School science teacher Bill Ebersol detailed the water monitoring and cleanup activity of about 55 students. Kids tested salinity, measured beach volume, studied sand composition and tracked current speeds, sometimes using such simple devices as a watch and a floating coconut. They also plan to do more intricate lab work to test for bacteria, Ebersol said.

"We're finding that the kids are enthusiastic," Ebersol said. "They're out of the classroom and actually watching these natural processes. We hope they're going to go home more environmentally aware."

Scientists have encouraged such partnerships and student involvement as one of the best hopes for making sure the bay stays healthy into the future.

Bret Yager can be reached at


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