E. coli source: Purdue DNA analysis rules out NSSD sewage spill

  The sea gulls did it. That's the conclusion of scientists at Purdue University's Calumet campus in Hammond, Ind., who have been studying last summer's high E. coli bacteria counts which frequently closed Lake County's beaches to swimmers.

  State Sen. Susan Garrett, D-Lake Forest, questions the accuracy of those findings.

  "I think it is irresponsible for the North Shore Sanitary District and the Lake County Health Department to put out this data until the public has had sufficient time to study the information. I still have many questions on this subject," Garrett said.

  Garrett said she is calling an early meeting, with a statistician present, to review the findings of the study.

  Charles Tseng, a professor of biological sciences at the university, said Friday that his findings from local beach and ravine water samples — provided by the Lake County Health Department from six locations — show through DNA analysis that feces from Lake Michigan sea gulls are the biggest contributor to E. coli flareups, not raw sewage overflows from the North Shore Sanitary District.

  Tseng said that for the past several months he has tested E. coli ribotypes of water samples and compared them with sea gull droppings, raw sewage and other contaminants.

  "Our results indicate that E. coli isolates from beach lake water and ravine (storm) runoffs match predominantly with those of sea gulls," Tseng said.

  He said ribotyping matches ranged from a low of 37.5 percent at Lake Forest Beach Ravine to 50.5 percent at Waukegan South Beach, compared with sewage samples of 2.5 percent taken at Lake Forest Beach Ravine to 14 percent at Highland Park Rosewood Ravine.

  Tseng said additional animal sources were also matched, but "the figures were too low to be of significance," he said.

  "Based on these results, one may assume that sea gulls were an important contributing factor for the E. coli contamination of these beaches," Tseng said.

  Brian Jensen, general manager of the sanitary district, said the conclusions confirm his belief that raw sewage was not the prevalent cause of the beach closings last summer. He added that interest from NSSD's board was so keen in finding the source of the contamination that it authorized the $26,000 university study, taken in cooperation with the Lake County Health Department, which provided the water samples.

  Garrett said she finds it hard to believe that sea gull droppings are the chief cause of last summer's E. coli beach closings — from the Wisconsin border to the Indiana state line.

  Neither does U.S. Rep. Jan Schakowsky, D-Evanston, or several other Cook County officials, including Gov. Rod Blagojevich, who last summer blamed the problem on excessive dumping of raw sewage into Lake Michigan by the Milwaukee Metropolitan Sewerage District.

  Schakowsky and other Illinois legislators have demanded that the U.S. Environmental Protection Agency enforce the Clean Water Act to halt regional sewage dumping into the lake.

  EPA Administrator Christine Whitman has said there is no direct evidence linking the Milwaukee discharges with E. coli-related beach closings in northern Illinois.