Water Quality at Lake of the Ozarks

USGS/Missouri S&T Lake of the Ozarks Sampling

The United States Geological Survey, Missouri University of Science and Technology and the Missouri Department of Natural Resources are cooperating on a research project to better understand water quality at the Lake of the Ozarks.

USGS and Missouri S&T have collected water quality data under a sampling plan developed in collaboration with DNR. The areas sampled include Grand Glaize Beach Cove at Lake of the Ozarks State Park and adjacent coves. Preliminary data is now available, and DNR expects USGS and Missouri S&T to present analysis of the data to the department before the end of the year.

The preliminary data, which has not yet been quality assured but appears reliable, includes sample results for E.coli as high as 5,300 colony forming units per 100 mL of water in a small tributary near Grand Glaize Beach. It is the policy of the Department of Natural Resources to close state park beaches if E. coli levels exceed 235 cfu/100 mL.

These results are sufficiently higher than the sample results at the other locations sampled for this study, including those taken at the beach, and suggest a need for additional scientific work. DNR will work with its partners to fully understand this preliminary data and to determine what caused the tributary sample results to be higher than those at the other locations. The department will keep the public apprised as this work moves forward. This project and others like it across the state help the department solve environmental problems and improve the quality of life for all Missourians.

USGS/Missouri S&T summary chart
USGS/Missouri S&T data

2007-2011 Lake Ozark Watershed Alliance (LOWA) and
DNR Lake of the Ozarks Water Quality Study

In October 2011, the Department of Natural Resources, working with volunteers from the Lake of the Ozarks Watershed Alliance, completed a five-year cooperative effort designed to establish baseline water quality data for the Lake of the Ozarks. Over the course of the study, the department analyzed 1,619 water samples collected during the recreational swimming season. These samples were tested for E. coli, whose long-term or excessive presence is considered a good indicator of possible water quality issues.

The sampling began in 2007 from coves beginning at the Bagnell Dam end of the lake and continued each season moving up the lake through the 2011 recreational season, eventually ending at Truman Dam. In total, samples were drawn from 118 coves at the lake.

At the end of each season, the department determined the geometric mean for that season’s sample results. A geometric mean is a statistical method used to analyze data collected over a period of time. The Missouri water quality standard for waters capable of supporting swimming and similar whole-body contact recreation is a seasonal geometric mean of 126 E. coli colonies per 100 milliliters of water. The annual geometric means for the survey data were 5.0, 7.6, 8.8, 3.8, and 3.0, from 2007 through 2011, respectively.

Additional information is available in the study’s final report: Water Quality Survey Report – E. coli Concentrations in Lake of the Ozarks.

 Recreational water safety information is available on the Missouri Department of Health and Senior Services' website at http://health.mo.gov/safety/recreationalwater/index.php.

Lake of the Ozarks Low-Impact Landscapes for a Healthy Lake of the Ozarks

In February 2011 the Department of Natural Resources awarded a $740,000 grant to the Lake of the Ozarks Watershed Alliance for a four-year project to address stormwater-related pollution affecting the Lake of the Ozarks. Additional information on the grant, including results of water quality sampling, is available here.

Lake of the Ozarks Initiative

On Sept. 23, 2009, Gov. Jay Nixon directed DNR to conduct a sweeping enforcement initiative aimed at improving water quality at the Lake of the Ozarks. Included in this initiative:

Initiative report

Baseline study of contaminants

Sampling for the water quality study began in October 2009. 78 sites were sampled and were analyzed for volatile organic analysis (VOA), pesticides (507 and 508), petroleum fractions, total nitrogen, total phosphorus, non-filterable residue (NFR), chloride, E. coli and total alkalinity as CaCO3.  Field measurements of dissolved oxygen, pH, specific conductivity, temperature and nephelometric turbidity were also recorded at each site.

2009 Inspection sweep

The inspection sweep began on Oct. 5, 2009, and the department cited more than 150 violations. There are more than 400 wastewater facilities near the Lake of the Ozarks or its major tributaries with DNR-issued operating permits. A map of the facilities included in this inspection sweep is available online.

Total Inspections Facilities in Compliance Noncompliant Facilities
419 264 155

State Park Beach Sampling

The Division of State Parks, a division of DNR, operates designated public beaches at 14 state parks throughout Missouri, including two beaches at Lake of the Ozarks State Park.  From May through October of each year, water samples are taken and analyzed weekly from these beaches. The DNR laboratory tests the samples to determine if water quality is safe for swimming. When bacteria readings reach certain levels, beaches are closed to the public until the next sampling determines the water is safe for swimming. Information about the current status of park beaches is available on the Missouri State Parks website at mostateparks.com. Signs indicating the status of the beaches are posted at the beaches as well.