A puddle of water in a Brooklyn crosswalk has persisted for so long that some residents can’t remember the last time they saw the ground beneath its depths.

The putrid pool at Erasmus Street and Rogers Avenue in Flatbush has perplexed and enchanted nearby resident Elizabeth Perez, who began documenting it last summer. She said the tepid water remains on the pavement even when it hasn’t rained for days.

In a series of almost 100 photos and videos, she’s captured how the urban tidal pool’s biome evolves with the seasons, delighting and disgusting her friends on Instagram.

Perez said life finds a way in the Flatbush puddle, which she’s seen grow as wide as 9 feet.

“All the algae was blooming and sometimes the water would be really clear and you could see all the way down and there were little bugs swimming around in it,” she said. “People love it. People love the updates.”

During the brutal winter, the puddle “was just like a giant ice block,” Perez said. “I think that there was a moment where it was dry, like, during the drought or something. That was the only time I remember.”

Some locals don’t find the phenomenon to be whimsical, but rather a sign the neighborhood needs more investment from the city so that people aren’t forced to dodge murky waters to cross the street.

The evolution of a crosswalk puddle, as documented by Brooklyn resident Liz Perez.

“The city has to come in and say, "We have to treat all our New Yorkers the way we treat New Yorkers in Manhattan, the way people downtown are treated,” said Jill Durant, whose mother owns a beauty salon near the puddle.

The puddle sits at the foot of what will soon be a residential development, which is currently surrounded by a green plywood construction fence strewn with trash.

”Money has to come first. And the money isn't allocated towards us. It goes to other places,” Durant said.

About a half-mile away at the corner of Nostrand Avenue and Sterling Street, Paco Abraham has a puddle of his own. Abraham was less amused, with the pool sitting just steps from the subway station entrance and a bus stop. Last Wednesday, a chicken bone trailed lazily along the puddle's surface as straphangers heaved themselves across it.

“Morning rush hour, you have hundreds of people an hour,” he said. “ It's absurd that we assume that this is OK. It's a little thing, I know. But come on. At a minimum, let's not have to jump over a lake to cross the street.”

Abraham said he’s reported the puddle to the city to no avail, and that the city Department of Environmental Protection is perfectly capable of coming up with a solution rather than closing out his complaints.

“There's a lot of talented people that work in this city. There could be a solution. But just closing it out, saying, like, ‘Eh, it's not a problem.’ No. That's not a solution,” he said.

Down the way at Sterling Street and Rogers Avenue, another pool of water has stood for so long that neighbor Henry Herring, who has lived on the block for more than 30 years, can’t remember when it was dry.

”It’s been here for a while. Every time it rains, it comes. I live up there for 30-some years. Never seen it dry,” he said.

Department of Environmental Protection spokesperson Rob Wolejsza said the agency ordered crews to respond to each of the three puddles and found that their infrastructure was up to par. He said the root of the problem appeared to be the way the streets were paved.

Transportation department representatives did not immediately respond to questions as to whether their paving practices produce puddles.

Perez said she’s willing to say goodbye to the puddle and others like it, even if it disappoints her followers.

“People that live in this neighborhood deserve a nice space,” she said. “I’m sure it’s making a lot of people's lives difficult. I think that my fans and the puddle's fans will, they'll cope.”