Swimmers and boaters have been asked to steer clear of Marina Park after tens of thousands of gallons of sewage overflowed, and authorities are still trying to figure out how bad the contamination is.
Word in the neighborhood is spreading quickly as people come across signs warning visitors to stay away.
The overflow couldn't have come at a worse time. The sun is finally shining and temperatures could reach the 80s by the weekend.
"People are already walking around in shorts and it's not even that hot yet," said mom Michelle Motley.
Another, more unpleasant, thought is also creeping in.
"I bet somebody's going, 'Oh, poop.' Literally," said boater Debra Pelletier.
The King County Waste Water Division said Thursday that around 68,000 gallons of sewage poured into Lake Washington for a full hour at Marina Park.
It was enough to cut off access to the water.
The county says the overflow started at a Kirkland pumping station a few blocks away, where transmitter malfunctions caused a cascade effect in the system and led to the leak.
"Accidents are going to happen, but it's just really gross," Motley said.
The county will keep the beach closed until at least Saturday as they test the site. Right now, it's not clear what's in the water, but residents don't want to take any chances.
"Who's going to get sick? Who's going to get giardia? Who's going to get c-diff, one of those disgusting diseases that you can get from fecal matter," Motely said.
On a weekend that would be perfect in the water, beachgoers know they'll be better on the shore.
"Warning. Danger, Will Robinson," Pelletier said.
The spill comes just three weeks after Seattle and King County settled a federal lawsuit over the hundreds of millions of gallons of waster water that flow into local waters each year.
They'll pay $1.4 billion in upgrades, along with a $750,000 fine.