Befouling of Chicago beaches doubted
Milwaukee’s 2004 sewage dump probably wasn’t cause, study
By Steve Schultze and Marie Rohde
Posted August 24, 2005
Milwaukee's record sewage dumping during May 2004 probably
didn't cause Chicago beach pollution a few weeks later,
according to new research aimed at settling a dispute
spawned by Windy City politicians.
The soon-to-be published report probably won't be the
final word, however.
Parts of it lend support to the traveling-sewage scenario,
showing that lake flows from Milwaukee have reached as
far south as Waukegan, Ill., within 20 days.
Richard Whitman, one of the report's authors, said Wednesday
that untreated sewage dumped into Lake Michigan from Milwaukee
indeed could foul Chicago beaches - even if Milwaukee
sewage wasn't to blame for the spate of closures in June
Heavy rains that May led to massive discharges of untreated
sewage by the Milwaukee Metropolitan Sewerage District
into Lake Michigan. The district initially pegged the
volume at 4.6 billion gallons, but later substantially
revised the figure downward, to 1.7 billion gallons.
Chicago Mayor Richard Daley and U.S. Rep. Mark Kirk (R-Ill.)
were quick to pounce on Milwaukee for that dumping, with
Kirk dubbing it "Cheesehead sewer water" and
Daley opining that "it's going to float down here."
This week, spokesmen for Daley and Kirk ratcheted down
the rhetoric some, stressing cooperative efforts to fend
off beach pollution all over Lake Michigan and the other
"I don't think any city should be off the hook,"
said Rita Athas, Daley's deputy chief of staff, when asked
whether the study exonerated Milwaukee. "Putting
4 billion gallons of sewage in the Great Lakes can't be
a good thing."
MMSD Executive Director Kevin Shafer said Wednesday that
he wasn't familiar with the study's results. He has previously
rejected the notion that MMSD's dumping could affect Chicago
Surviving the cold water
Whitman said sewage-borne bacteria under some circumstances
could survive the lake chill as hitchhikers on host particles
and take the 90-mile swim to Chicago.
"It remains a good possibility" that some of
the Chicago beach pollution comes from "imported"
pollutants, said Whitman, who heads the U.S. Geological
Survey's Great Lakes Science Center.
"The (Milwaukee) overflow causing a (Chicago) closure
a week later is unlikely," he said. Bacteria from
a Milwaukee sewage dumping could, however, "show
up three, four, five weeks later" in Chicago, Whitman
Other research by Whitman and others has shown that bacteria
that attaches to organic debris can live at least several
months in beach sands and lake sediments, he said.
MMSD has dumped more than 14 billion gallons of untreated
sewage since the deep tunnel system was completed more
than a decade ago, though none this year.
The dumping is the subject of a longstanding federal
pollution lawsuit and ongoing state probe. The district
has pledged to do nearly $1 billion in additional improvements
to reduce sewer overflows.
Whitman's name is attached to the study, which suggests
that the untreated sewage dumped by MMSD into the lake
from May 10 to May 25 last year could not have reached
Chicago beaches by June 20, when several were closed because
of high bacteria counts.
The research was launched last year based on a request
by Kirk and Daley.
That study also involved researchers from the U.S. Environmental
Protection Agency, the National Oceanic and Atmospheric
Administration and the University of Wisconsin-Milwaukee.
They based their conclusion on lake currents, satellite
photos and testing for E. coli bacteria in the Milwaukee
harbor around the time of the sewage dumping.
A computer simulation
David Schwab, an NOAA oceanographer and another study
author, said a computer simulation done for the study
showed that water from the Milwaukee River during the
May 2004 sewer overflows was "very unlikely"
to reach Chicago by the time high E. coli readings were
found at Chicago beaches.
Much of the MMSD dumping was into the Milwaukee River.
Lake currents vary with the wind, but the predominant
direction is southward, Schwab said. Significantly, his
computer model showed Milwaukee River water reaching as
far south as Waukegan, Ill., within 20 days.
The study did not attempt to determine whether the flow
from Milwaukee after the big sewage dump had any impact
on beaches between Milwaukee and Chicago, said David Rockwell,
an environmental scientist with the EPA and one of the
study's four authors.
"We'd have to look at that more precisely because
those areas are closer to Milwaukee and the possibilities
are greater," Rockwell said.
Bacteria died within days
Sandra McLellan, the UWM researcher on the study, said
water samples taken from the Milwaukee harbor during the
May 2004 overflows suggested bacteria died off within
a couple of days.
"Once (bacteria) starts to disperse in Lake Michigan,
it really dies off quickly," said McLellan, who works
for UWM's Great Lakes Water Institute. Other pathogens
- viruses and protozoa - live longer, but it's not clear
how much longer, she said.
Whitman cautioned that sampling at relatively shallow
depths "doesn't tell you anything." Bacteria
that get to beaches, lakebed sediments and algae do live
longer, he said.
"There is a free exchange of what is in the sand
and what is in the lake," he said.
The focus on affixing blame for a set of beach closings
might be misplaced.
Whitman said a complex series of interrelated factors
affects pollutants around Lake Michigan, with sewer overflows,
runoff and other bacteria sources contributing.