News Release 334

Follow-up sampling at Lake of the Ozarks finds E. coli level at site falling, but still above federal guideline level

Volume 38-334 (For Immediate Release)
Contact:  Judd Slivka

JEFFERSON CITY, MO, JUNE 7, 2010 –  Resampling of the single Lake of the Ozarks cove that exceeded federal E. coli guidelines for public swimming areas last week has yielded another result that exceeds those guidelines.

A sample taken June 4 from the southwest side of Porter Mill Hollow had a result of 275.5 E. coli colonies per 100 milliliters of water, exceeding the federal standard of 235 cfu/100ml.

Department staff drew three results from the cove last Friday. Two of the results were under the federal standard. The result that exceeded the standard was still lower than the June 1 sample, which was 325 cfu/100ml.

 Porter Mill Hollow is located southwest of Hurricane Deck on the Osage Arm of the Lake of the Ozarks.

The samples drawn on Tuesday were the first in a series of monthly samples that are taken between May and October at designated areas of the lake. The purpose of the program is to develop a five-year baseline that will assist in future studies of the lake’s health.

This year marks the fourth of a five-year program, with the department 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 coves tested last week will be tested again in July. The department will test a different set of sites 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 single-sample standard of 235 E. coli colonies per 100 milliliters of water.

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 Monitoring results will be posted to the map as they become available.