General Contact Number: (530) 621-5567

Environmental Health

Septic System Minimum Setback Requirements

To protect water supply sources, surface water, and the proper function of a septic system, it is important to meet certain setbacks. Please refer to the following tables.  


Leach Lines

From ephemeral (seasonal) stream/swale 
50 feet
From flowing stream100 feet
From well, spring, lake, or pond100 feet
From lake or reservoir used for drinking water200 feet
From trees
5 feet
From lot lines, roads, driveways, or buildings8 feet
From a cut or fill (downgradient)
 Four (4) times the cut or fill height  
​From a swimming pool
​10 feet
Shall not be placed under asphalt, concrete, or under areas subject to vehicular traffic 
Shall not be placed in fill material  

Septic Tank

From house5 feet
From any building
5 feet
From trees5 feet
From lot lines, roads, or driveways5 feet
From streams, springs, lakes, or reservoirs50 feet
From well or spring used for domestic purposes
100 feet
​From a swimming pool
​5 feet
Shall not be installed in areas subject to high groundwater tables  



Minimum horizontal separation distance between well and: 
Any sewer line (sanitary, industrial, or storm; main or lateral)50 feet
Watertight septic tank or subsurface sewage leaching field100 feet
Cesspool or seepage pit150 feet
Animal or fowl enclosure100 feet
The above horizontal separation distances are generally considered adequate. Wells should be located outside areas of flooding. The top of the well casing shall terminate above grade and above known levels of flooding caused by drainage or runoff from surrounding land. Area drainage should be directed away from the well, and if necessary, the area around the well shall be built up so that the drainage moves away from the well.