Three of 10 weekly samples of Morgan Hill water tested positive
for coliform bacteria Monday and one of the three also tested
positive for E. coli. A retest Tuesday showed no signs of the
bacteria, leading officials to believe the problem was with the
test, not the water.
Three of 10 weekly samples of Morgan Hill water tested positive for coliform bacteria Monday and one of the three also tested positive for E. coli. A retest Tuesday showed no signs of the bacteria, leading officials to believe the problem was with the test, not the water.
The city’s weekly tests are performed by Monterey County Laboratories.
Jim Ashcraft, director of Public Works, said he reported the positive tests to the California Department of Health Services and, following their direction, had more complete retests performed and increased the levels of bacteria-fighting chlorine in the water.
City Manager Ed Tewes notified the City Council Wednesday night and the public will be officially notified within two weeks, through newspaper ads.
“This is totally unprecedented,” Ashcraft said. “In the past five years, only once before – in November 2003 – has any test come up positive.”
Norma Arceo, spokesperson for the state DHS, said it is normal for tests to come up “false positive” occasionally.
“It is because of the nature of the test,” Arceo said. “They are so sensitive; if a finger gets inside the testing bottle it could trigger a false positive.”
Arceo said the second round of tests are final. She said there was no chance the bacteria could have disappeared within 24 hours between tests.
Theresa Lam, water quality specialist for Monterey County Labs, said the positive test is uncommon but believes there was no contamination.
“Usually, when you get a positive there is a contamination in the system,” Lam said. “But the repeat (tests) pinpoint exactly where it is but we didn’t find anything.”
Lam said she was not sure how a contamination could have entered the test sample.
“It could have been a sampling error or the weather could have been windy and something blew into the sample,” she said.
City workers collect the samples in sterile containers and send them to Lam, who conducts the tests.
“We test whatever they bring us,” Lam said.
Monterey County Labs also tests water for the cities of Monterey, Gonzales, Soledad, Greenfield and for private well owners and small municipal systems as well.
Ashcraft said the distance between the location of the positive sites was puzzling.
“It’s odd that two of the sites were near downtown and the third at the north end of Holiday Drive (in the east foothills),” Ashcraft said.
The other two sites were on Calle Mazatan, near El Toro School and on Keith Way, near Tennant Avenue and Monterey Road.
Every week 10 different sites, rotated from 40 sites in every part of town, are tested for bacteria and other impurities. If the water tests positive for any bacteria, a retest is taken from five houses up and five houses down the street from the test station, located just behind the curb, Ashcraft said.
“This way we are sure to get a bigger confirming sample,” he said. “And they all were negative.”
The test stations are about 24” high and 8 inches around with a protective lock, looking a bit like a cable television box.
Ashcraft said the levels of chlorine detected during both tests were normal, further leading him to believe that the bacteria was not actually present in the water.
“When chlorine attacks bacteria the level (of chlorine) goes down,” he said.
“There is no cause for alarm,” Tewes said, “and no bacterial contamination in our system.”
As always, he said, residents should consult their health professionals if they have concerns. While bacteria was found, there is no level or count to report because a test is “pass/fail” – it’s either there or it’s not there, Ashcraft said. There is no acceptable level of coliform or E. Coli bacteria in a water supply.
The city’s water supply comes entirely from underground wells. The water is stored in one of 10 reservoirs.
In April 2002 a drinking fountain at Encinal School in Coyote Valley showed signs of coliform during a routine test. It’s confirming test also showed negative though the Morgan Hill School District shut down the fountain as a precaution.
Details: www.morganhill.ca.gov or 779-7271.
