LIHU‘E — Heavy rains over the past couple weeks have made some coastal waters on Kaua‘i unsafe until further notice, health officials and local experts said.
The state Department of Health issued a Brown Water Advisory on Feb. 24 that remains in effect for the eastern shores of the island from Nawiliwili Bay to Hanalei Bay. The public is advised to stay out of flood waters and storm water runoff due to possible overflowing cesspools, overflowing sewer manholes, pesticides, animal fecal matter, dead animals, chemicals, pathogens and associated flood debris. The severe storms last week have only compounded the problem of high levels of enterococcus, an indicator of feces contamination.
On Friday, the indicator bacteria counts for Nawiliwili Stream in Kalapaki Bay were more than 232 times the allowable level, according to Dr. Carl Berg of The Surfrider Foundation’s Kaua‘i Chapter. The bacteria count measured was 24,196 per 100 ml. The count in the Kalapaki surfbreak was 12,033 per 100 ml., more than 115 times the allowable level, he said. “Stay out or at least make sure to shower after being in polluted water,” Berg said.
The nonprofit’s Blue Water Task Force collects monthly samples at surfbreaks and streams around the island. The DOH gathers water-quality monitoring data on a weekly basis, though not at all the same sites as the task force.
The Garden Isle’s beaches and surfbreaks were mostly clean last year, Berg said. But some were quite dirty, especially after heavy rains that cause runoff from the land.
During water quality monitoring, water samples are collected and enterococcus are cultured and counted in a 100 ml water sample, he said. In a single sample the count must not exceed 104 bacteria per 100 ml. The geometric mean, or average, of five samples should not be more than 35 bacteria per 100 ml.
The DOH data for 2010 was collected by DOH staff in approximately mid-calf deep water on the beaches, Berg said. A total of 44 different sites were sampled over the course of 2010, but only 10 sites were collected on a weekly basis over the course of the full year.
DOH data for frequently collected sites is presented in Table 1. The sites are listed from cleanest on down to most commonly polluted. Note that seven of the 22 sites are clean and never exceeded the single sample “polluted” standard and most are polluted less than 10 percent of the time, Berg said.
Only the Hanalei River mouth at Weke Road, the mouth of Limahuli River and Hanama‘ulu Beach were polluted greater that 25 percent of the time and all had a geometric mean greater than 35 colonies per 100 ml., he said. “This suggests that pollution is mainly coming from river water,” Berg said in an e-mail Saturday. “The Hanalei River site has been posted for years with two signs warning of possible contamination by sewage. Note that not all of the county parks on Kaua‘i are even tested regularly (e.g. Niumalu, Lucy Wright, Kealia, Kekaha and Hanama‘ulu).”
A comparison of DOH data from 2009 and 2010 reveals seven increases and seven decreases in geomean values among the 14 sites that were collected both years, he said. Data for all three Hanalei beach parks suggests they are getting cleaner. Table 2 lists the offshore surfbreaks and streams that the Surfrider Foundation’s Kaua‘i Chapter samples on a monthly basis and tests for enterococcus bacteria. The nonprofit uses the same test as the DOH, Berg said. The sites are listed from cleanest down to most commonly polluted.
“The most important thing to note is that 10 of the 19 surf sites never exceeded the single sample standard and had very low geometric means, i.e. they were really clean,” he said. “The ones of most concern are those where they were polluted more than 25 percent of the time. Nawiliwili Stream in Kalapaki Bay and Niumalu Beach Park, near the Huleia River are consistently polluted. Pakalas surfbreak, off the stream area, also has a high geomean count.”
Surfrider, with assistance from Kaua‘i High School and Kaua‘i Community College students, is doing more extensive weekly sampling in Kalapaki Bay to determine the sources of the high enterococcus bacteria concentrations there, Berg said.
“For the 19 sites sampled by Surfrider both the geomean values and the percent exceedences are much lower in 2010 when compared to 2009,” he said. “This may reflect sampling after fewer storms or changes in levels of pollutants entering the ocean (e.g. Pakalas).”
The most recent values for Surfrider Foundation’s Kaua‘i Chapter samples taken on the second Saturday of each month can be found at: www.surfriderkauai.ning.com
The most recent values from the DOH are posted on their website at: http://emdweb.doh.hawaii.gov/CleanWaterBranch/WaterQualityData/default.aspx