A cypress of some sort; it could well have a Phytophthora infection.

Or has an unusually large dog been peeing on it?

Resin

Yeah, a doggus giganticus! ;0)

Wow that puppies gotta go....and it looks like he did.
Sorry Zephyer couldn't resist.
It reminds of some agricultural herbicide application on a windy day I have seen a few times usually right next to big
field of dying grass and weeds.Probably not the situation
here.Doug

Did you or anybody go in under the tree and look at it?
Bark missing on some limbs, etc.
Also, sometimes people will poison trees not on their property for the view. When I was landscaping I was asked several times to do that. I refused, of course.
Mike

Thanks for the responses. Wish it were some kind of huge doggie pee. Mike and Doug, I did consider herbicide might be the cause but the front of the tree also shows lots of browning as indicated in the next photo. The bark and branches look good. Some have suggested it could be a result of low moisture from a few years ago.

Another photo.

I've had more damaged/dead trees this spring than I can ever recall. I attributed it to last year's heat and drought.

tj

Did you cut into the bank in front of the Thuja plicata in the last few years and damaged the roots? Usually they're pretty forgiving about that. I've cut a few roots of Western Red Cedars while making roads on my property with a bulldozer a time or two and they seemed unaffected.
Another cause could be that you put down mulch in the late spring and didn't water thereafter, denying the roots of water for the rest of the summer.
Your new lawn looks like it's free of weeds. What about a 'Weed and Feed' fertilizer? The roots of the tree might extend out into the lawn. Or, while making the lawn, the soil was skimmed off to make the lawn smooth and the tree's roots were damaged.
Mike...grasping at straws here.