Crystal Lake is back open for swimming, as state lab tests show the E. coli levels in the water are back down within safe levels.

Mayor Marc Laredo announced on Friday that the lake had been shut off to swimming because of high E. coli levels and that the city would have the water tested every weekday until levels were back down.

The wait was shorter than expected. On Tuesday afternoon, Laredo sent out an announcement that the lake was safe and back open.

This was the second closure of Crystal Lake in the span of six weeks—the first was in late June due to cyanobacterial algae—as a persistent drought scorching air temperatures have teamed up to create fertile conditions for microbes.

And there’s still a cyanobacterial algae bloom in the Charles River that’s causing concern.