"That is really the pollution we are most concerned about in Tahoe," said Jesse Patterson, Deputy Director of Keep Tahoe Blue (The League to Save Lake Tahoe).
Patterson says run-off is the lake's biggest source of fine sediments and the biggest source of reduction in lake clarity.
"(Fine sediments) stay suspended in the water and they make it so you can't see down as far," said Patterson.
The first step in preventing those particles from getting in the lake is knowing where they are coming from. To learn that, Keep Tahoe Blue uses volunteer 'pipe keepers.'