QUESTION: As a follow-up to whether it is safe to swim in or eat fish from the Ala Wai Canal in the April 9 Kokua Line (is.gd/AVN3Mv): Because Waikiki and Ala Moana are so close to the Ala Wai, I’m sure pollution gets pushed to both beaches. I’m also sure both beaches are monitored, but is that information public?

ANSWER: The information is posted on the website of the state Department of Health’s Clean Water Branch, which monitors beaches statewide. (See is.gd/NZELuV.)

However, the spread and frequency of monitoring declined following the state’s layoffs in 2009, said Watson Okubo, supervisor of the Monitoring & Analysis Section.

That resulted in four out of five Oahu monitoring positions in the Clean Water Branch being eliminated.

Despite that, beaches continue to be monitored and findings posted online. (See below for an explanation.)

The Ala Wai Canal can be characterized as "an urban sink," Okubo said, agreeing with a description given previously by Gary Gill, the Health Department’s deputy director for environmental health. "But it does its job and allows sediment for the most part to settle out before reaching Magic Island."

When sedimentation builds up, the canal is dredged, he said. That’s happened twice since he’s been with the department, in 1978 and 2004. The only other time the canal, built in 1928, was dredged was in 1968.

In 2006 an aging sewer force main in Waikiki burst, prompting officials to divert millions of gallons of raw sewage into the canal.

At that time, Okubo said, health officials observed the plume of sewage flowing out of the canal and learned that it "dog-legged" toward Diamond Head for about three-fourths of a mile mile, then headed out to sea toward Ewa.

"This was clearly visible from the top of the (Hawaii) Prince Hotel, and current drogues (devices used to measure currents) deployed daily by the (city) documented this," he said.

Daily water tests by the Health Department and city showed that the contaminated waters did not sully Ala Moana Beach, but did affect Magic Island lagoon.

Also affected were surf sites at Ala Moana Bowls, Rock Pile, Kaisers, Fours and Threes, where bacteria levels were found to be elevated fronting the Hilton Hawaiian Village and Hale Koa hotels, Okubo said. Warning signs were posted at affected beaches.

WATER QUALITY

While results of the beach monitoring can be found on the Water Quality Data website, to find out whether you should avoid certain beaches, go to is.gd/QD41e7. Current warnings and advisories about unacceptable water conditions will be posted there.

As for "normal" day-to-day postings, it helps to know the terms used. Definitions can be found at emdweb.doh.hawaii.gov/cwb/wqd/viewer/Glossary.aspx.

The two main bacteria monitored are enterococcus and clostridium, which basically are found in human and animal fecal matter.

As for what the numbers mean: two numbers, both EPA-standard levels, are used to evaluate levels of enterococcus: a geometric average of 35 cfu (colony-forming units) per 100 ml (milliliters), and a single sample maximum of 104 cfu/100 ml.

The values on the website would most easily be compared with the 104 level, a Clean Water Branch official explained. If a value ">104" is found, it indicates that at that moment, at the area where the sample was taken, enterococcus levels were above 104 "for some reason."

"It’s important to realize that it does only represent that moment the sample was taken, because a chance event such as a duck or monk seal swimming by can influence the levels of the sample," the official said.

Meanwhile, a clostridium value of 50 is used in tandem with enterococcus levels as a secondary-indicator bacteria to better evaluate the data.

"Any beach that is over the levels would not be flagged on the map where all the sampling sites are shown," the official said.

If a beach is assessed as a health risk, it will be flagged on the current warnings and advisories webpage.

Write to "Kokua Line" at Honolulu Star-Advertiser, 7 Waterfront Plaza, Suite 210, 500 Ala Moana Blvd., Honolulu 96813; call 529-4773; fax 529-4750; or email kokualine@staradvertiser.com.