Canal study detects sewage
BY TRAVIS JAMES TRITTEN
keysnews.com
A high number
of Florida Keys canals are contaminated with sewage, according to a
water quality study released Tuesday by The Nature Conservancy.
The 18-month
study shows that many of the tested canals contain high levels of
enterococcus bacteria and low dissolved oxygen levels -- both are
indicators of poor water quality. Tests also revealed viral pathogens.
"Our findings
are definitive proof that human sewage has contaminated canals
throughout the Keys," said Jody Thomas, director of the Conservancy's
Keys program.
Rains may be
washing sewage from leaky septic tanks and cesspits through porous
limestone into canals or open water, according to the conservation
group's report.
Over the
course of the Florida Keys Watch study, a series of 17 canals located
throughout the Keys were sampled at regular intervals.
Six of 10
stations tested positive for the presence of human-borne viruses. More
than half of the 17 samples collected during the wet season -- May
through October -- tested positive. During the dry season, from November
to April, no viruses were detected in nine samples.
The presence
of viruses confirms that human sewage is present in the canals,
according to The Nature Conservancy.
Enterococcus
sampling found that 36 percent of the 112 samples collected following a
heavy rainfall contained levels that violate federal Environmental
Protection Agency standards for the bacteria. Enterococcus is a type of
bacteria present in the intestines of warm-blooded animals and is
considered to be a reliable indicator of human sewage.
Following a
period of no rain, only 6 percent of the 360 samples collected prior to
sampling contained such high levels.
The water at
nearly half of the 17 test stations had dissolved oxygen levels lower
than the state minimum of 4 mg/liter of oxygen during the wet season.
Only three of the stations fell short of state standards during the dry
season.
Without
appropriate dissolved oxygen levels, aquatic animals become stressed or
die.
Thomas said
the next step is to determine if pollutants in wastewater such as
caffeine, household cleaners or estrogen from birth control pills are
adversely affecting the health of nearshore marine species like the
queen conch.
Scientists
from Florida Marine Research Institute have determined that conchs spawn
offshore, but stop spawning when brought inshore.
The
Conservancy reported the test results to the Florida Department of
Environmental Protection, the state Department of Health and homeowners
near the testing areas.
The group will
also present its findings at a meeting of the steering committee for the
Water Quality Protection Program of the Florida Keys National Marine
Sanctuary on Feb. 29 in Marathon. |
