Why does the Lake get closed? How long is the Lake posted if high levels of E. Coli are detected?

If a high bacterial level is found in a swimming area, such as Memorial Park Beach or Community Center Beach, the Sharon Board of Health will require the beach to be closed. Repeat testing is then carried out quickly to see if bacterial levels have changed. In more than 80% of cases statewide, bacteria decreases to a safe level before the first test results are reported. In most cases, subsequent testing results in lower readings of bacteria. Often the initial reading stems from a transient source of contamination, rather than a persistent source, such as a faulty septic 4 system.
Signs warning of high bacteria levels are required when:
● Two samples collected on consecutive days both exceed the single sample water quality standard, or one sample exceeds it and a re-test is not collected the following day.
● One sample exceeds the water quality standard at beaches where, in two or more of the last four full seasons, samples collected on consecutive days exceeded the water quality standard.
● The geomean standard is exceeded.
● Preemptive: Assumption of bacterial exceedance after rainfall/storm event based on historical data. ● Physical quality: Presence of solid refuse, floating waste solids, oils, grease, scum, or hazardous materials.
● Safety hazards: Presence of dangerous conditions, including fast currents, sharp drop-offs, water clarity/visibility issues.
If a high bacterial level is found in a non-swimming area, the potential sources of contamination will be evaluated. Swimming beaches, however, may remain open if their specific bacterial levels are within regulatory standards, and there is no possibility of direct contamination to the swimming areas.

Generally the levels of the E. Coli are reduced within 24 hours of the conclusion of the rainfall. However; the 24 hour incubation period remains for that resample to be tested. Because of this it is common for bathing beaches to be closed for a day or two to ensure public health and safety.