Ask Mr. Smarty Plants

According to this USDA Plant Profile Map, Taxodium distichum (Bald cypress) is not even native to California, but since you have been growing it for 20 years and also since California is the world capital of plants that are native to somewhere else, we will not consider that as a problem. As you can see from the pictures from our Image Gallery below, the Bald Cypress happily puts up knees in just about any damp situation. Knees develop mostly in poorly drained sitations, which obviously a leachfield is. The fact that your leachfield is so far from the tree itself demonstrates vividly what we keep telling our visitors: that there is much more to a tree underground than is visible above ground.

So, obviously the tree is doing just fine. The question is, how is your leachfield doing? Since we know a lot more about tree roots than we do leachfields (which is zip) we will have to do a little research on whether you need to take any action. Turns out Mr. Smarty Plants has already answered a question on tree roots in leach fields. This article on Septic Plant Problems concerns trees that were deliberately planted on top of the leach field; the advice there was to cut down the trees and remove them. That's pretty harsh and your tree with the offending roots is 90 ft. away, for goodness sake.

Frankly, we think this is out of our expertise. We would recommend you have an expert in septic systems look at the situation. Obviously, you don't want to cut down the tree; perhaps cutting out the offending roots would suffice for a while, but you can bet the tree will send roots right back to its dinner table.