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Effect of Low Impact Landscaping (LOWA LILs) On Lake Contamination
(The Geosyntec Project)

The "Geosyntect Project" is part of the LOWA 319 Grant designed to demonstrate the long-term effect that LOWA LILs have on the E-coli concentrations and on nutrient pollutants in the Lake of the Ozarks.

Program Description

Under this program, 9 coves in the focus area are being tested for phosphorus, nitrogen, total suspended solids, and E. coli. Three of the coves are undeveloped, 3 coves are treated by a regional waste water treatment plant, and 3 coves are with septic tanks.

During the first year (2011), these coves will be sampled in a 20-week water collecting program (run by Geosyntec with volunteers providing the boats, captains, and collecting), then a focused program of LOWA LILs will be encouraged, and then in the grant’s 3rd year, another 20-week water collecting program will happen.

Samples are analyzed by Lake Ozark Environmental and the results verified by Geosyntec through the grant.

Year One Study Is Complete

The discussion below reflects completion of the first year of this study. The 20 week study on these same coves will be repeated in 2013.

The teams of LOWA volunteers who religiously collected these samples in a timely fashion week after week are to be highly congradulated. LOWA thanks each and every one of them.

E-coli Test Results

E-coli test results were available within a few days of the sampling events and reported by Geosyntec to MODNR, LOWA, and the county and state health departments where elevated results were investigated.

What the E-coli Test Results Mean

E-coli test results are reported as "MPN" which stands for "Most Probable Number" of E-coli colonies per 100 milliters of water. This is a typical biological test in which water samples are incubated at a set temperature for a specific length of time in the presence of a culture which is specific to e-coli growth. The number of colonies thus resulting is counted and reported in these studies as MPN per 100 ml of water.

This E-coli testing has been used for a number of years as the standard method of indication of biological contamination of water because the E-coli thus detected are thought to be specific to the guts of warm-blooded animals and therefore a "marker" for potential contamination. While most E-coli strains are harmless, some are extremely dangerous so that the presence of high concentrations of E-coli increases the odds of the presence of a dangerous strain. Standards have been set as guidelines indicative of safe "full-bodied" contact (such as swimming from public beachers). In Missouri, the standard that is followed for public beaches is that recommended by EPA which is:
1.A single-sample recommended maximum level of 235 E. coli colonies per 100 milliliters of water for public swimming areas.
or
2. A geometric mean of 126 E. coli colonies per 100 milliliters of water. A geometric mean is a statistical method used to analyze data collected over a period of time.

E-coli Test Results to Date

See LOWA comments and results below and also see an interactive Google map containing all the sample sites with data.

All the raw data is also available on the MODNR website.

Four sample points were sampled in each of nine coves. The complete data set is shown in the DNR site identified above and also in the above cited map. The first graph below shows the average results of those four sample points for all nine coves. Cove 2 had some abnormally high results, particularly during the week 10 sammpling event. The second graph therefore shows the average results for all coves excluding cove 2.

Week 10 data for Cove 2 has therefore been eliminatated from the "Rain Effect" and "Septic Tank Effect" graphs.

Cove 2 abnormalities are under investigation by Missouri DNR. E-coli concentrations in Cove 2 were greatly reduced to a very safe level in subsequent weeks

Residents of the area reported that, during the week-end preceding the week 10 sampling, they had used their deicers the entire weekend in an effort to bring cooler water to nearer the surface for benefit of swimmers. This was not done on subsequent week-ends.

As can be seen from the graph, the test results for all the coves, excluding Cove 2 during the abnomalities discussed above,continue to show very good quality lake water.

"Rain Effect" and Septic Use" Effect

Although the data may be too scarce to be statictically valid, the next two graphs are nonetheless very interesting in that they do demonstrate the effect heavy rains can have on the average E-coli concentration in the Lake coves. Also, the final graph demonstrates the average results to date of the three cove sets of:

• 1. Populated with septic tanks (note: Cove 2 is excluded from data set)
• 2. Served by a regional sewer system
• 3. Relatively undeveloped

The Rain Effect

The graph below presents the average E-coli concentrations from all sample points collected following a rain event versus the average of that from events collected without such a rain event (except that week 10 for Cove 2 has been eliminated from this data set)

Type Cove Effect

The graph below shows the average results of the E-coli concentration in those coves served by septic systems versus those served by a regional sewer system versus those that are relatively unpopulated. (Again, Week 10 of Cove 2 has been eliminated from this data set)