Bacteria levels have mostly returned to healthy levels in the waters of coastal Alabama, just in time for the Fourth of July holiday. Only three sites tested for bacteria levels higher than the “safe to swim” threshold.

ADEM, the city of Daphne and Mobile Baykeeper all test the local waters at various locations for enterococcus, a bacteria that is a common cause of infections, according to the National Institutes of Health.

Mobile Baykeeper, which runs the Swim Where It’s Monitored (SWIM) program from April-September, measures the bacteria level as a “Most Probable Number” (MPN), a statistical measurement. According to the EPA, the “safe to swim” threshold for enterococcus in MPN is 104. The “safe to swim” threshold for E. Coli is 235 MPN, though E. Coli bacteria is only measured at one site.

ADEM measures the level of enterococcus as number of bacteria colonies per 100 milliliters. The threshold in that measurement is 104 per 100 mL.

Several sites did not have updated water quality testing results available. Those are listed as “Not updated” in the chart. Sites with the note “retest” means that the water was resampled a day later after the first water quality test came back with high levels of bacteria.