The Department of Health recently tabulated the results of water quality measurements taken throughout 1992 at sites on Kaua’i, O’ahu, Maui, and the island of Hawai’i. For Lana’i and Moloka’i, the DOH released bar graphs showing average water quality at four areas (two for each island) over the last four years.
The standard for marine recreational waters in Hawai’i is no more than seven enterococci colony-forming units per 100-milliliter water sample. (This is stated as 7 CFU.) Federal guidelines are more liberal: 35 CFU.
In general, high enterococci levels are associated with beaches that receive a large amount of freshwater (surface or underground). The highest average enterococci level – more than 100 CFU – was found at the shoreline near the mouth of the Waimea River on Kaua’i. First and second runners-up are on the Big Island: Waiakea Mill Pond in Hilo (about 68 CFU) and Kolekole Beach County Park near Honomu (about 56 CFU). When rains cause freshwater flows to increase, as happened almost daily in February, water quality diminishes even more.
Beaches whose average enterococci levels exceeded 14 CFU were rated “very poor.” Across the state, 11 recreational areas were determined to have “very poor” water quality. Areas where the average CFU was between 7.5 and 14 were described as having “poor” water quality. Fourteen beaches fell into this category (four on Kaua’i; six on the Big Island; four on O’ahu). “Compromised” beaches were those whose average CFU was between 6.6 and 7.4; there were four “compromised” areas in 1992 (one on the Big Island, one on Kaua’i, three on O’ahu).
Twenty-nine beaches statewide were rated “excellent” (less than 1.5 CFU). This does not include the Kailua Bay outfall, which, though given an excellent rating, is not a beach. Other areas where water quality was measured also are not “recreational beaches” in the strict sense. Despite this, the rankings give one a good idea of relative coastal water quality across the state.
Kaua’i
Twenty-six recreational shorelines were measured on Kaua’i for 1992. The worst water quality was found, as indicated earlier, in the area where the Waimea River meets the ocean. Koloa Landing was next-worst on Kaua’i, with about 43 CFU. Other very poor ratings were assigned to Waimea Landing (about 30 CFU); Hanalei Bay Landing (about 18 CFU); and Hanomaulu Beach (17 CFU).
“Poor” ratings were assigned to Kalaipaki Beach; Kalihiwai Beach; and Port Allen Pier. Nawiliwili Coast Guard Pier was rated as “Compromised.”
O’ahu
The worst water quality on O’ahu is found where Kaelepulu Stream meets Kailua Bay. The water quality there averaged 35 CFU per 100 milliliters.
Rated “poor” were Fort DeRussy, Kuhio Beach, Kaiaka Bay, and Kokokahi Pier. “Compromised” beaches were Kahana Beach Park; Wai’alae-Kahala Beach; and Haunama Bay.
“Fair” beaches were: Kahanamoku Lagoon; Gray’s Beach; Kahanamoku Beach; Hau’ula Beach Park; Kiaona Beach; Tavern Beach; Lanikai Beach; Haleiwa Beach Park; and Ala Moana Beach (center area).
Maui
The worst water quality on Maui was found at Honomanu Bay shoreline, which was the only area on the island to receive a “very poor” rating, with 22 CFU.
Hawai’i Island
Rated “fair” were Hilo Bay near the lighthouse; Kapoho Beach Lots No. 1; Richardson Ocean Center; and Puhi Bay stations 1,2, and 3. “Compromised” waters were found at Kailua Pier A.
“Poor” ratings were given to Puako Beach Lots (sample station FE); Leleiwi Beach Park; the Ice Pond (off Hilo Bay); Keaukaha Beach; Hilo Bay boat landing; and the canoe beach at Hilo Bay.
“Very poor” water quality was found at Waiakea Mill Pond; Kolekole Beach County Park; Honoli’i Cove; and the Wailoa River.
Lana’i and Moloka’i
Measurements for 1992 show both of Lana’i’s sampling stations at Manele Boat Harbor and Hulopo’e Beach to have excellent water quality (1.5 and 1.1 CFUs respectively). On Moloka’i, measurements taken at Kaunakakai averaged 4.5 CFUs (“good” water quality), but at Kalaeloa, the average was 35.4 CFUs (“very poor”).
In 1989, however, the situation on Moloka’i was reversed, with Kaunakakai averaging 26.4 CFUs and Kalaeloa 5.3 CFUs. Similarly, in 1989, the water quality at Manele Boat Harbor was “very poor” (with 52.1 CFUS) and no more than “fair” at Hulopo`e Beach (5.5 CFUs).
Eugene Akazawa, of the DOH’s Clean Water Branch, states that the large variation in average readings for Lana’i and Moloka’i sites is not something to which a great deal of importance should be attached. Water quality readings can vary dramatically with weather conditions, so when averages are based on a relatively small number of readings as they are for Lana’i and Moloka’i – such things as an occasional heavy rain can result in skewed averages.
A Search for Meaning
But apart from Lana’i and Moloka’i, how valid are the water quality ratings as an indicator of water safety?
If waters where enterococci levels exceed state standards are unsafe, then it would seem that some of the state’s most popular recreational waters should be placed off-limits. However, the Department of Health posts warning signs on beaches only when waters are known to be contaminated by spills of untreated or partially treated sewage.
Actually, the presence of enterococci bacteria may not be a good indicator of water safety for humans. Enterococci are found in soil and animal wastes. Usually, when near-shore waters receive large quantities of runoff or freshwater flows, enterococci levels rise – thus the connection between inland flows and water quality, as measured by the presence of enterococci bacteria, mentioned earlier.
But if enterococci levels bear little relation to risks to public health from exposure to contaminated water, why should the state use enterococci as its health standard?
According to Akazawa, the state is trying to come up with a better indicator than enterococci. The Clostridium perfringens bacteria are one strain under consideration as a possible replacement, Akazawa told Environment Hawai’i.
At present, the Department of Health is undertaking a study of water quality at the Kuhio groin, in Waikiki. The object, Akazawa said, is to “relate non-point source [runoff] output to health risks.” When that study is completed, the state may be in a better position to reevaluate its use of enterococci as a measure of nearshore water quality.
Water quality ratings for recreational waters may be requested from the Department of Health Clean Water Branch on O’ahu: 808 586-4309.
— Patricia Tummons
Volume 4, Number 9 March 1994
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