Another, not much better.

There are not a lot of alders around here, but my understanding is that they are a pioneer species and don't live long. I am actually surprised yours are growing that far south. I thought native alders crap out around zone 6 or 7. Is yours exotic?

Exotic...ha! Planted here in abundance by home builders as they grow so quickly. Not so much any more.
Taking them down and planting a mature replacment will be$$$ yikes! I could ask an arborist, but hate spending money on a lost cause, as I suspect these are. Oh woe is me.

The native California Alder Alnus rhombifolia is found in wet places. Is that the one you have? They expect a lot of water--are not drought tolerant. Could be the drought. The roots are pretty aggressive so I got rid of mine, and don't miss them.

Here is a link that might be useful: comments on A. rhombibolia

Hi hb,
Since I didn't plant them some thirty years ago, I don't know the species, but would guess it is the rombibolia, though hard to think it's native in our dry area. Still, very popular with builders awhile back. So much so, that it's inique aroma was a nostalgic "California scent" to me after we left the state and returned a few years later. We held many a birthday party " under the spreading Alders" :) No longer lovely , but dread the expense of taking them down and finding another tree. Too difficult to judge by the pic, but thought I'd ask anyway. Thanks. :) marti