Humans Not to Blame for Beach Bacteria

Some of Chicago’s most popular beaches had bacteria levels above amounts considered safe on more than one out of every five days last summer, according to a national report on beach water quality released Wednesday by the Natural Resources Defense Council.

The report found that Rainbow Beach, Montrose Beach, 31st Street Beach, South Shore Beach, Calumet South Beach and 63rd Street Beach all registered levels of E. coli bacteria that exceeded government safety standards on at least a fifth of summer days in 2010.

Other area beaches fared worse in the report. Two beaches in north suburban Winnetka — Elder Park Beach and Centennial Dog Beach — had among the highest levels of E. coli in the state last summer, exceeding the federal standard 61 percent and 49 percent of the time, respectively. The Indiana Dunes National Lakeshore beach – a summer destination for many Chicagoans – exceeded the standard one third of the time. And Jerose Park Beach in Northwest Indiana near the outflow of the Grand Calumet River had high bacteria levels 75 percent of the time.

The federal Environmental Protection Agency’s standard for unacceptable levels of bacteria is an amount that is expected to make 0.8 percent of swimmers sick to their stomachs, based on government research. Chicago issues water quality advisories at that level and swim bans at bacteria levels that are expected to make 1.4 percent of swimmers sick. Federal law mandates beach water be tested at least once a week for E. coli.

Yet Chicago beachgoers are likely at less risk from human sewage than people in other Great Lakes cities, said Cathy Breitenbach, lakefront operations manager for the Chicago Park District.

That’s because the Chicago River carries sewage away from Lake Michigan, even during heavy rainstorms. In Chicago, untreated sewage is released into the lake only about once a year during extremely intense storms, according to the Metropolitan Water Reclamation District of Greater Chicago. In other Great Lakes cities, untreated sewage is more commonly released into rivers that empty directly into the lake, according to EPA figures.

Nationwide, the report found bacteria levels are highest after heavy storms, since contaminated storm water runs into lakes and oceans and sewage systems become overwhelmed, forcing the release of untreated sewage.

In Chicago, Breitenbach said, waste from seagulls — not humans — is the main culprit in high bacteria levels.

“I think our beaches are actually pretty clean,” she said.

The Park District is trying some novel ways to reduce seagull populations at area beaches. City “ambassadors” are roaming beaches asking people to sign pledges that they will not feed the birds or leave litter that attracts them. And at two beaches, the Park District is using border collies to scare away gulls, an expensive but seemingly effective practice, according to Breitenbach.

At 63rd Street Beach, bacteria levels exceeded the standard more than half the time in 2006, 2007 and 2009, when no dogs were around, but in 2008 and 2010, when dogs were dispatched to “harass” gulls, excessive bacteria levels were found only 6 and 22 percent of the time, respectively. Similar results were found at 57th Street Beach during the same period, Breitenbach said.

NRDC water analyst Karen Hobbs said the dogs seemed to be successful in improving water quality at those beaches, but that “monitoring and disrupting gulls doesn’t get to the heart of the problem.”

She said the three main factors in high bacteria levels are the city’s aging sewage infrastructure, which causes some sewage releases into the lake; climate change, which is thought to cause more frequent heavy storms; and invasive mussels that facilitate the growth of cladophora, an algae that is a breeding ground for bacteria.

The NRDC and other environmental advocacy groups say beach water quality can be best improved by implementing more green infrastructure — including green roofs and permeable pavement that absorbs water — to prevent storm water from funneling into sewers, lakes and oceans.