An intense and damaging brown tide has surfaced in the Great South Bay, and it could devastate the young clam beds within the water.

Dr. Chris Gobler says brown tide is back for the first time in two years, showing up in the Great South Bay between Patchogue and Sayville.

"We know that brown tide occurs in areas where the water is stagnant, it's not moving a lot, also in areas where there's a high nitrogen load from land to sea," says Gobler.

Gobler says the sources of that nitrogen pollution are wastewater from household septic tanks and fertilizer, which are creating harmful conditions for the baby clams that spawned in the water just as the brown tide broke out.

One kayaker described the water as, "Thick as syrup ... it's brown like dark tea and it's not inviting to get into the water."

People in the area say they started seeing the water change color at the end of May into early June. Scientists say it could not have come at a worse time.

"We know that brown tide's toxic to the baby clams, so those ones that run into the brown tide are probably not going to survive," says Gobler.

Gobler says even with the ongoing efforts to reduce the amounts of nitrogen pollution going from the land and into the sea, brown tide is not an uncommon site in these waters, but it is unwelcome.

Gobler says he and his team sampled 30 sites from across Long Island to see if the brown tide is spreading. He will have results back later in the week.