Why have the TTHM levels increased in the drinking water?
The Mebane drinking water started showing increased levels of TTHMs beginning in 2007, although the annual average remained compliant until 2008. This time period coincides with the recent drought which also appears to have increased levels of organic matter (total organic carbons-TOCs) in the lake. The increase in TOCs resulted in higher TTHMs when the water is chlorinated. Recent data indicates that the TOCs in the lake are showing a decline with the increased rainfall and it is anticipated that TTHMs will also decline.
