Lake Okeechobee's polluted muck creates disposal
concerns
By Andy Reid
South Florida Sun-Sentinel
Posted July 8 2007
Elevated levels of arsenic as well as a soup of
pesticides and other chemicals were among contaminants found in thousands of
truckloads of muck recently cleaned out of Lake Okeechobee's drought-exposed
bottom.
Arsenic levels on the northern part of the lake bed were as much as four times
the allowable limit for residential land, according to newly released test
results from the South Florida Water Management District.
Independent lab tests of a sample taken by the South
Florida Sun-Sentinel show even higher levels on the eastern part of the
lake, exceeding what would be allowed to be spread on commercial and
agricultural land.
The district's test results are expected to guide decisions about how to dispose
of mounds of pollution-laden muck, scraped away by bulldozers and backhoes
brought in to take advantage of a drought that dropped the lake to a historic
low.
Spreading the muck on agricultural, commercial or industrial land, as well as
dumping it in landfills, is among the options proposed.
"We are evaluating how and where we dispose of it...so we don't create a
new problem someplace else," said Chip Merriam, the district's deputy
executive director.
While scraping away the muddy layer should breathe new life into the suffocating
lake bed, disposing of the black ooze could spread harmful pollutants elsewhere.
For example, mounds of muck are being temporarily piled on land intended to
become a water storage area that is one day expected to filter water headed to
the lake.
Some of the muck also could end up as the base of a parking lot planned at a
public campground and marina beside the lake.
The water management district contends the muck can be used safely, as long as
it doesn't end up on residential land. The muck proposed to be used for the
parking lot at the Okeetantie campground, on the northern rim of the lake, would
be covered by asphalt and out of reach of children and other campers."A
pesticide is a poison," said Herb Zebuth, a former scientist for the
Florida Department of Environmental Protection, who has worked on Everglades
restoration. "These are very complex chemical compounds. These things need
to be taken seriously."
Also, testing for many contaminants may show that individually the levels don't
raise concerns, but mix them together and the health and environmental
consequences may be unknown, Zebuth warned.
The muck that coats the bottom of the lake results from phosphorus, nitrogen and
other pollutants washed into the lake with stormwater that drains off farms and
lawns.
Those pollutants fuel the growth of algae and other plants that die and settle
to the bottom, forming a muddy layer that stifles the grasses that provide fish
habitat.
Removing the muck restores the lake's natural sandy bottom and fosters the
growth of tape grass, bulrushes and other native grasses needed for fish to
spawn and birds to feed.
Six weeks of scraping away the top 2 feet of muck, mostly from the lake's
northern and western edges, ended in June. During that time, district crews
collected more than 1.9 million cubic yards of muck — enough to fill about 950
backyard swimming pools, according to the district.
Although as many as 30 tests by the district at six locations revealed an
alphabet soup of pesticides and PCBs, all were at levels below the state's
allowable standards.
The elevated level of arsenic in the muck raised the most concerns. Arsenic and
other pollutants from pesticides can affect the lungs and nervous system, lead
to cancer and at high enough levels can be lethal.
The district's test results show arsenic at most sampling sites exceeding levels
allowed for residential land, but below state limits for commercial and
agricultural land.
The state standard for allowable levels of arsenic on residential land is 2.1
parts per million, and the limit for commercial and agricultural land is 12
parts per million.
At Eagle Bay Island, on the northern part of the lake, tests showed arsenic
levels at more than 9 parts per million. At Fisheating Bay, the western side of
the lake, the arsenic levels hit 4.5 parts per million. Eagle Bay Marsh, also on
the north side of the lake, had the lowest arsenic readings, topping out at 1.5
parts per million.
The district's tests indicate the muck can be
used on agricultural land and other commercial applications, as intended, as
long as recipients "understand what's in the material," said Susan
Gray, the district's Lake Okeechobee program director.
"You don't want to take this material and spread it on someone's garden
[but] there's no restriction for commercial use," Gray said.
A sample of muck tested for the Sun-Sentinel by
A&L Southern Agricultural Laboratories Inc. of Pompano showed an arsenic
reading of about 15 parts per million.
The sample came from exposed lake bed near Port Mayaca, on the eastern part of
the lake, not far from where district officials have held news conferences about
the drought's effects on the lake. The district is not digging muck from that
site.
The district would not comment on Sun-Sentinel test results. Agency
officials said their own findings were preliminary and contaminant levels could
come down after more evaluation.
Much of the muck dug from the lake has been piled on dry land inside the earthen
dike that surrounds the 730-square-mile lake.
Temporary storage sites outside the dike include property owned by Glades
County, west of the Harney Pond part of the lake. Muck also is being stored on
the district's Lemkin Creek property, pegged for a future water retention area,
and a nearby private property at the lake's northern bend.
The Audubon Society supports the muck cleanup, but disposing of the muck north
of the lake in areas that drain into the lake raises concerns about recycling
the problem, said Paul Grey, a scientist for Audubon of Florida.
"There is a concern that, 'Oh great, it will just flow right back into the
lake,'" Grey said. "If they do it wrong, it will be a problem."
Before dumping the muck at the temporary storage sites, district crews bulldozed
earthen berms several feet high to surround the muck and contain any runoff. And
though the sites are not lined, tests for "leachability" indicate the
harmful materials are not likely to soak into the ground, said Lake Okeechobee
program director Gray.
Storage at the Lemkin Creek property is just temporary and the muck should not
leave any pollutants that would hamper plans for water storage there, Gray said.
Andy Reid can be reached
at abreid@sun-sentinel.com
or 561-228-5504.