The PUD met the TTHM standards set forth by the GA Environmental Protection Division at all sampling sites except for the monitoring location on the southeast end of Barnett Shoals. The site is one of eight sampling locations throughout Athens-Clarke County.
The Georgia Rules for Safe Drinking Water and Title 40 CFR141.64(b) set the locational running annual average (LRAA) maximum contaminant level (MCL) at 0.080 mg/L. The LRAA of four-quarters is used to determine if a water system violates the MCL. When a new quarterly sample is taken, the oldest results are removed from the LRAA. Similar to how a poor grade has lasting effects on a GPA, the high 3Q2021 result, combined with the removal of the low 1Q2021 in the calculations, resulted in a violation for 1Q2022 despite the individual quarterly sample falling below the MCL.
PUD sampling results for 2Q2022 find the LRAA below the MCL and return the utility to compliance. The elevated 3Q2021 will drop from future calculations. With this increased test result rolling off the LRAA and the actions the PUD has taken to address elevated TTHMs, we anticipate the TTHM LRAA to remain below the MCL, as was the case for the past thirteen years since the EPA's Stage 2 Disinfectants and Disinfection Byproducts monitoring requirements began. The table below displays the quarterly results from this location.
|Barnett Shoals Road Quarterly Sampling Results|
|4Q2020||0.083||4Q2020||no longer in the calculation||4Q2020||no longer in the calculation||4Q2020||no longer in the calculation|
|1Q2021||0.040||1Q2021||0.040||1Q2021||no longer in the calculation||1Q2021||no longer in the calculation|
|2Q2021||0.077||2Q2021||0.077||2Q2021||0.077||2Q2021||no longer in the calculation|
|* Quarters are referred to as "Q." The number before Q indicates which quarter the results reference, and the last numbers identify the year. For example, 1Q2021 references the first quarter of 2021. |
** "N/A" is provided for samples not yet gathered.
*** LRAA refers to the Locational Running Annual Average, with a maximum contaminant level (MCL) of 0.080 mg/L.