Crumbling of Chicago Shore Mapped in Lake Michigan

Chicago’s Lake Michigan shoreline is crumbling. Looking back toward the city from the bobbing deck of this government research vessel, one can see the protective limestone breakwaters sag and dip.

The wavy lines on the maps that spill out of computers in the laboratory below deck disclose crumbling debris scattered on the lake bottom.

“Chicago has an armored shore and we’re looking at chinks in that armor,” said John Schlee, a U.S. Geological Survey geologist who is heading a two-week expedition to map part of Chicago’s shoreline.

Schlee and other scientists aboard the instrument-crammed, 38-foot-long Neecho are at work tracking underwater erosion that threatens hundreds of millions of dollars’ worth of Great Lakes region real estate, including Chicago’s famed Gold Coast, which has some of the most valuable urban property in the Midwest.

Sonar Devices

For 12 hours a day the boat, normally based at the geological survey research facility at Woods Hole, Mass., moves along part of Chicago’s 30-mile-long shore, towing sonar devices that send signals to map-generating computers. The instruments are locating places where erosion and storm-driven waves have begun to cause shoreline sea walls--some built 60 years ago--to crumble or collapse.

The project along the Chicago shore is the pilot phase of a proposed five-year, regionwide effort to track the damage being caused by record high water levels on the five Great Lakes and by powerful waves churned by Midwestern storms.

The study could eventually cost U.S. taxpayers tens of millions of dollars, and regional governments could spend far more to repair damage found by the study and to avert further damage.

The Great Lakes--Superior, Michigan, Huron, Erie and Ontario--are generally about one foot lower now than they were a year ago, when they reached their highest point since the region was settled more than 150 years ago. But the lakes, which border on eight states and hold 20% of the earth’s fresh surface water, remain higher than normal and “still a matter of concern,” said Owen Scott, a hydraulic engineer for the U.S. Army Corps of Engineers.

Costly Damage

High water levels and seasonal storms have been blamed for costly damage along much of the region’s 8,000 miles of shore.

In Chicago alone last year, one storm did several million dollars in damage to lake front property, roads and parks. Chicago’s main water filtration plant suffered a reported $1 million in damage during one storm on a single afternoon last February. Rep. Sidney R. Yates (D-Ill.), who represents one of the hardest-hit areas of the city, persuaded the U.S. Geological Survey to send the Neecho and its crew for the pilot program.

Schlee said that in addition to mapping erosion, his team and geologists from the Illinois State Geological Survey will study the “geologic history of lake levels . . . to see if (high and low) water cycles can be predicted.”

Researchers will also study the strength of waves and currents as they strike the shoreline.

“When we think of lakes we think of smaller bodies of water,” said Michael J. Chrzastowski, a coastal geologist with the Illinois Geological Survey. “But (Lake Michigan) behaves like an ocean. We don’t have tides or currents but we have wave energy comparable to oceans.”

Congressmen’s Group

Concern over lake levels and damage caused by storms moving across the lakes has resulted in the creation of the Lake Levels Congressional Network, made up of congressmen from the region. They are supporting a bill sponsored by Rep. Robert W. Davis (R-Mich.) that may eventually cost $10 million a year for 10 years to develop new shoreline maps and to determine where structures need to be built to dissipate wave energy before it can damage property.