Before I yard planted metasequoia in Texas I would compare the climate to what St Louis had last year. Our record setting heat and drought, which might be normal for your area, would probably have killed my decade old metasequoia if not for this ridiculously heavy watering schedule I went to. Now it was rough on many of our natives also and maybe mine was just acclimated to the climate it knew its whole life, but I don't know how much heat and drought metasequoia is built for.

I've got a dawn redwood planted in my front yard in South Jersey. It grew 4-5 feet in the first two years. Last year, the ends of the needles started to turn brown. Then every "leaf" on the branch started turning brown and died. I did some research and discovered that it may be causes by something similar to "Sudden Oak Death" syndrome. It's caused by a water mold pathogen. In addition to Oaks, scientists believe it may now be affecting Dawn Redwoods and other trees, as well. You can't overwater Dawn Redwoods. Related to the Bald Cypress, the Dawn Redwood soaks up water like a sponge and loves it. But, this isn't the problem. Dawn Redwoods can get a fungal pathogen that causes the needles to turn brown and eventually the entire branch becomes infected and dies. The fungal spores are spread by water and other affected trees nearby. No chemical on the market seems to kill the pathogen. Scientists suggest cutting the affected branches, removing the tree, etc. that isn't an option for me. I spent a lot of money on my baby and I'm not getting rid of it. I have a feeling the recent wet spring weather we've had here may be the cause. I got a copper based fungicide that I'm going to try. This fungal canker has already killed my two nectarine trees. So there you have it. Sudden Oak Death has destroyed about a million oak trees in California. And, this fungal pathogen I've just described is decimating Redwoods. The disease is called: Botryospheria Dothedia. Or Redwood Canker. As I said, it's a fungal disease. Almost impossible to treat and kill. That's why I'm trying a copper based fungicide spray. Anything is better than watching my dawn redwood slowly croak each day.

davidrt28 is absolutely correct. If the OP is speaking of the foothills of the Sierras, then Coast Redwoods wouldn't stand much of a chance without additional irrigation. If they are in the foothills of the Coast Range, then I'm very confused because they shouldn't need any additional irrigation whatsoever. FWIW, I have a couple Sequoia sempervirens in my zone8 Washington garden for several years. They got supplemental irrigation for their first year or two in the ground. After that, they've been totally on auto-pilot and are doing great. @php, I agree with Ken. Those Sequoia are ugly and probably won't get better. If you are indeed in the Sierra foothills there are a couple of awesome pines (Pinus sabineana and lambertiana) that are well suited for you. In fact the latter, aka Sugar Pine will get quite large and both create amazingly large cones. ~Dave

I don't think it's "zone pushing" to plant a Metasequoia in Zone 8/borderline 9 (especially in one that's typically WET). And I may be wrong, but I don't think you even had a very hot summer this year. If it were a question of being zone inappropriate, I think you'd have a more gradual decrease in vitality (over a few years). Is it possible it was planted too deeply? Also, when in the Spring was it planted? Was it in full leaf at the time? (Guessing it was.) How long has it been leafless? Try scratching just beneath the trunk with your fingernail and see if there is any green; if there is, it may still re-foliate. Otherwise, I'd try again. Probably less stressful if you can get one that is leafless (in late Winter/early Spring..., depending on where it's coming from if you're ordering from a non-local source. They tolerate wet soils quite well and seem non fussy about soil BUT they do are sensitive to salt (as in a coastal environment or snow melt in the North). Good luck!