One user, Ayah E Arek-Arek, expressed concern over the photo getting into “the bad hands of hoax spreaders,” while other users said that the waters reminded them of blood.
Pekalongan is known for making batik, which is a traditional Indonesian method of creating patterns and drawings on fabric, using wax to resist water-based dyes.
It is apparently not uncommon for rivers in Pekalongan and the surrounding area to change colour, according to Reuters. Another village north of the city was also swamped with green coloured water last month.
He confirmed that the photographs were genuine and added: “It will disappear when it mixes with rain after a while.”
The dye was not toxic or dangerous, reported AFP. They added that officials used pumps to drain the area, clearing it in less than an hour.
Indonesia is no stranger to flooding, especially during the rainy season, and at least 43 people were killed when a storm hit the capital Jakarta earlier in the year.
The country has previously used a technique known as cloud seeding to try and induce rain before it hits more flood prone areas.
According to Reuters, this involves firing salt flares into the clouds from planes, in the hope that this will cause them to burst earlier than they would otherwise do.