Hidden in the cracks of the road, they are barely visible to the average driver - except as a plume of dust coming off a high-speed vehicle.
Fine sediments, fine particles. Whatever the name, these minute pieces (smaller than a human hair) are the culprit for Lake Tahoe's decreasing clarity, according to numerous scientific studies.
But some street sweeper manufacturers are working to stop the villain at its source, and collect fine particles off of roads before they have a chance to work their way into watersheds.
"Street sweep technology has come a long way," said Dick Minto, road supervisor for Washoe County. "There have been a lot of steps in broom technology over the years to get the small particles off the ground."
Newer technology helps keep the lake cleaner, Minto said.
"It's so fine like flour, and it's such an issue to try and pick it up," Minto said.
Washoe County and a number of other stakeholder agencies at Lake Tahoe were privy to a demonstration of one of those sweepers, the Tymco DST 6 Regenerative-Air, earlier this week.
"We're not endorsing any product," Minto said. "Our goal is to find out what is best for the lake and keep up with the latest technology and the best that is out there."
Washoe County now uses a Sentinel street cleaner that also works to pick up fine particles.
Other ski areas in Colorado have used the Tymco model to reduce fine particles, said Bill Tuttle, a sales representative for H&E Equipment Services which distributes Tymco products. He also said there are 12-15 of the models in use in Las Vegas.
The city of Toronto did a study on the Tymco product and found that it removed 90 percent of the materials on the road and deposited less than 1 percent back onto the sidewalks. One Tymco model can cost about $210,000, Tuttle said.
At Wednesday's demonstration, a track of dirt and debris was laid out at the Incline Station of Washoe County Roads. The Tymco was then driven over the lane of dirt, leaving a clean trail behind it.
The product works by using a series of brooms and depositing the fine particles into a hopper in the sweeper. The hopper can then be emptied and its contents transferred to somewhere less environmentally sensitive.
In Washoe County's case the sediments extracted from the Sentinel sweeper are taken to a landfill near Lovelock.
Officials also demonstrated the street cleaner's capabilities by driving over a pile of fine sediments, showing the machine's efficiency.
"We separate the fine materials, anything that would normally go into the airstream," said Bob Hatfield, a Tymco representative who was at the demonstration.
The demonstration was purely informative and Washoe County is always on the lookout for new technology, Minto said.
"The whole effort is to keep Tahoe clean," Minto said.