News Release 328

Lake of the Ozarks testing finds one sample with elevated E. Coli levels

Volume 38-328 (For Immediate Release)
Contact:  Judd Slivka
573-751-1010

JEFFERSON CITY, MO, JUNE 3, 2010 – Water testing at the Lake of the Ozarks Tuesday found one sample out of 54 with an E. coli level in excess of federal guidelines for public swimming beaches, the Missouri Department of Natural Resources announced today.

The sample, taken from Porter Mill Hollow, had an E. coli level of 325.5  colonies per 100 milliliters of water, slightly less than one and one-half times the U.S. Environmental Protection Agency’s recommended maximum level of 235 for swimming areas.

Three other samples taken in the same cove, which is located southwest of Hurricane Deck on the Osage Arm, had levels below the federal maximum.

Department staff will be returning to the coves this week to take follow-up samples. Inspectors from the department’s Southwest Regional Office in Springfield will also begin inspections of permitted facilities that may drain to the cove to determine if any of them are contributing to the elevated E. coli levels.

In the fourth year of a five-year program, the department is testing samples taken from 105 sites along the lake’s Gravois Arm, its Osage Arm from Mile Marker 36 to Mile Marker 60 and from three sites that had been part of previous years’ testing. The purpose of the program is to develop a five-year baseline that will assist in future studies of water quality at the lake.

These coves will be tested again in July. The department will test a different set of sites in later this month and continue alternating testing the two sets of sites through October, with each site being tested three times over the course of the summer.

The state water quality standard for swimming and related whole body contact recreation is a geometric mean of 126 E. coli colonies per 100 milliliters of water during the entire recreational season. A geometric mean is a statistical method used to analyze data collected over a period of time.

Because the state standard requires data collected over the entire summer before a determination is made, the department reports monthly results as compared to EPA’s recommended single-sample maximum of 235 E. coli colonies per 100 milliliters of water for public swimming beaches.

E. coli is a bacteria found in the intestinal tract of warm-blooded animals, including humans.  While most strains of E. coli are harmless, some can cause gastrointestinal illness.  The testing process used in this study does not differentiate between strains.

These bacteria and other pathogens can reach lake water from many different sources, both human and animal.  For some people, such as children, elderly or those with weakened immune systems, even low levels of these bacteria may cause illness.

The sampling program is a partnership between the Department of Natural Resources, Lake of the Ozarks Watershed Alliance and Ameren UE. When completed, the program will have collected sampling data from coves from Bagnell Dam to Truman Dam.

A link to a map of the areas being sampled is available on the department’s website at dnr.mo.gov/loz/index.html. Monitoring results will be posted to the map as they become available.

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