Q – With all the homes being built on and around Badger mountain in the Tri-Cities, is there any danger of landslides, similar to what is happening at Rattlesnake Hills? I’m unfamiliar with the geology there, and I understand that building homes can affect stability, but are there other likely dangers in that area that potential homebuyers/builders should be wary of?

A – There have been prehistoric landslides (now stabilized) on Badger Mountain along with the other ridges nearby. These may have occurred following one more of the Ice Age floods >15k years ago.

Renewed landsliding is unlikely as long as there is no significant addition of water that could load the slope and/or lubricate weak zones within, or between, basalt flows – leading to instability. Badger Mountain itself is probably safe since there has been little new development on top or on the steeper sides of the mountain. Most of the mountain is now free from future development, thanks to the Friends of Badge Mountain, who have turned most of the mountain into a preserve. (One exception is the group of new Sterling homes built at the west end of the ridge).

Other unprotected ridges may not be as lucky. The cluster of new homes built on top of and along the sides of Little (East) Badger Mountain could generate stability problems, especially if excess water used for landscaping is allowed to percolate underground. There are also a number of new roads dug into the steeper north side of the ridge that potentially could undermine and destabilize the slopes above. Adding irrigation water to these slopes will only increase the likelihood of slope failure in the future. – Bruce Bjornstad