Water quality along Maui's shorelines ranked high in a national report that analyzed water pollutant levels at nearly 50 of the island's beaches.
Only 2 percent of Maui beaches that are monitored by the state Health Department exceeded maximum bacterial standards last year, according to an annual beach water quality report released this week by the Natural Resources Defense Council.
The New York City-based environmental group has the mission of "safeguarding the earth, its people, its plants and animals and the natural systems on which all life depends."
Honolua Bay in West Maui, shown here in a photo taken last year, had the highest levels of beach water contamination among 47 Maui beaches last year, according to a national report by the Natural Resources Defense Council. The report was based on water quality monitoring by the state Department of Health.
The Maui News / MATTHEW THAYER photo
The state as a whole ranked seventh best among 30 states evaluated in the report, down from last year's ranking of being the fourth cleanest in the nation.
Statewide, 4 percent of Hawaii beach water samples exceeded public health standards for pollutants, up from 3 percent in the previous year's report.
Nationally, the state with the best ranking was Delaware, followed by New Hampshire and North Carolina. On the opposite end, Louisiana, Ohio and Illinois had the highest violation rates, the study found.
The report noted that the majority of Hawaii's beach water contamination was due to heavy rainfall and storm runoff.
The study looked at data for a total of 47 beaches on Maui that the state Health Department monitors either twice a week or twice a month. Hawaii's beach water monitoring program is carried out by the department's Clean Water Branch.
The report found that samples at 11 of those Maui beaches - or 2 percent - exceeded the state's daily maximum bacterial standard of 104 colonies per 100 milliliters.
The so-called exceedance levels - the percent of samples at individual beaches that exceeded standards - ranged from a low of 1 percent (at Kamaole Beach Park III and Kanaha Beach Park) to a high of 50 percent (at Honolua Bay). Two beaches on Kauai - Glass Beach and Hanapepe Bay - also had a 50 percent exceedance rate, the highest among the 161 beaches monitored in Hawaii.
The Department of Health tests for enterococcus, a bacterial microorganism found in human and animal waste, as well as Clostridium perfringens, a tracer for human sewage. Samples are taken 1 foot below the surface in water that is knee-to-waist deep.
The report said most of Hawaii's beach water contamination is tied to heavy rainfall, with less than 1 percent of contamination related to sewage spills or leaks.
It is unclear from the report why Honolua Bay's exceedance level was so high last year.
The state Health Department did not immediately respond to requests for additional information about Honolua Bay.
The Maui office of the Aquatic Resources Division under the state Department of Land and Natural Resources says heavy rainfall in the area causes surface runoff into the bay, which contributes to poor water quality.
A 2007 study by University of Hawaii researchers also points to sediment runoff from rains as impacting water quality in Honolua Bay.
That report was prepared for landowner Maui Land & Pineapple Co. by the university's Department of Natural Resources and Environmental Management.
"Turbid water conditions occur from runoff and stream flow during rainfall events and through sediments during windy conditions," the study said. The researchers also noted that because Honolua is a bay, pollutants that settle in the bay can get trapped for up to six months.
The Natural Resources Defense Council said in its report that the U.S. Environmental Protection Agency is responsible for ensuring that recreational waters are safe for swimming. But it notes that those standards have not been updated since 1986.
The EPA has proposed draft standards as required by the federal Beaches Environmental Assessment and Coastal Health (BEACH) Act of 2000, which are expected to be finalized in October.
"The EPA has recommended bacteria levels as 'safe' in recreational waters even though the agency estimated they would permit one in 28 swimmers to become ill with gastrointestinal sicknesses," the Natural Resources Defense Council said. "The EPA should revise the level of acceptable risk when it finalizes its new standards this fall so that they are more protective of public health."
The report also looked at the number of beach contamination warnings and advisories issued last year.
The state Department of Health issues warnings for bacterial exceedances and sewage advisories. It also issues brown water advisories when it determines that storm water will cause water quality problems, including debris and dead animals in nearshore waters, the report said.
Total warning and advisory days in 2011 amounted to 1,246 days for all Maui beaches, the report showed.
The following are some of the Maui beaches included in the study and what percent of samples exceeded the state's contamination standards:
* Hanakaoo Beach Park, tested twice a week: 3 percent.
* Honolua Bay, tested twice a month: 50 percent.
* Hookipa Beach Park: tested twice a month: 0 percent.
* Kaanapali Beach, tested twice a month: 0 percent.
* Kahului Harbor, tested twice a week: 4 percent.
* Kamaole Beach Park I, tested twice a week: 0 percent.
* Kamaole Beach Park II, tested twice a month: 0 percent.
* Kamaole Beach Park III, tested twice a week: 1 percent.
* Kanaha Beach Park, tested twice a week: 1 percent.
* Kihei (off St. Theresa Church), tested twice a week: 6 percent.
* Launiupoko State Wayside Park, tested twice a week: 2 percent.
* Makena Landing Beach Park, tested twice a month: 0 percent.
* Napili Bay, tested twice a month: 0 percent.
* Wailea Beach Park, tested twice a week: 2 percent.
* Nanea Kalani can be reached at email@example.com.