2024 Season - Wet Weather Groundwater Determinations & Percolation Testing: Closed for the Season

Groundwater determinations and percolation testing are necessary for onsite wastewater treatment systems (OWTS) in unincorporated Sonoma County.

• Groundwater determinations closed for the season in all testing areas.
• Percolation testing closed for the season in all testing areas.
  

(Testing areas: Cloverdale, Guerneville, Healdsburg, Petaluma, Santa Rosa, Sebastopol, and Sonoma)

Rainfall totals data and/or testing dates are valid as of April 24, 2024.

More Information: Wet Weather Groundwater Determinations & Percolation Testing