Chesterton Tribune

Scientists tell new method for predicting lake swimming safety

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The U.S. Geological Survey’s Great Lakes Science Center has announced a new method of predicting bacterial contamination in Lake Michigan that public officials can use to help decide when to close a beach to swimming.

Each morning, USGS scientists will download data from weather and water monitoring stations located near or around the Burns Ditch outfall and beaches to the west. They will incorporate the data into a mathematical model, determine the likelihood of elevated bacteria levels, and forward the results to beach managers.

The USGS has proposed using this method for other Great Lakes beaches.

Up until this year, the monitoring procedure involved testing for E. coli, an indicator of fecal contamination, but a one-day lapse occurred between the time the samples were collected and the results.

Dr. Richard Whitman, the USGS scientist leading the new project, said the delay often meant that a beach closed a day too late to protect swimmers on the first day of high bacterial counts and unnecessarily left it closed a day after the bacteria cleared.

To develop mathematical models, USGS scientists studied beaches in Porter and Lake counties last summer. Dubbed Project SAFE (Swim Advisory Forecast Estimate), the model uses measurements such as rainfall, river input, wave height, and lake turbidity to estimate E. coli counts and to determine when counts are high enough to threaten the health of swimmers.

Project SAFE has been funded by a federal grant through the Beach Act of 2000 and the Gary Sanitary District. Scientists will use the data from this second year to validate the model. The Gary Sanitary District will match the 2005 Beach Act funding to allow USGS to continue the research.

Project SAFE seeks to decrease the waiting time for results by incorporating real-time information into its model prediction, according to an USGS news release.

The Indiana Department of Environmental Management just recently announced a change in policy allowing beach managers more flexibility to determine when to close a beach, due to the concerns about the validity of the E. coli testing procedure. Indiana Water Quality Standards specify that E. coli counts shall not exceed 235 colonies per 100 milliliters for swimming.

The Indiana Dunes National Lakeshore’s beach monitoring report issued today shows that all National Lakeshore beaches were well within that water quality standard based on samples collected Wednesday. The highest reading was just 31 colonies/100 ml at Porter Beach.

The National Lakeshore urges beach goers not to swim or play in streams or ditches flowing into Lake Michigan, since they contain runoff that is more likely to be contaminated; not to feed the seagulls or other animals on the beach, since the feces can increase microorganisms in the beach and in the water; to pick up pet waste and dispose of properly; to use a hand-sanitizing lotion (62 percent ethyl alcohol) after swimming or playing in the sand; to support wetland restoration, since wetlands help clean and protect Lake Michigan; and to reduce water use, especially during heavy rains when sewage treatment plants get overloaded.

To obtain information on other Lake Michigan beaches in Indiana, go to


Posted 6/3/2005