One of two Alaskan cedars (Chamaecyparis nootkatensis) is distressed, now the second year this is noted, and perhaps the decades old tree will not be around for much longer. While diagnosis is not a simple matter, I suspect the cedar has been too shaded for too long. Branches on the shadier side have been bare for years, and now the less shaded side is fading. I blame this on a reasonable expected lifespan, and not as an error in judgment in planting where the evergreen would eventually fail. So much for excuses.
The Alaskan cedar was once planted with exposure to morning and afternoon sunlight, with a shady midday respite. But, as the garden and the forest bordering the garden have grown, the hours of sun have diminished, and now there is only a brief late afternoon period of filtered sunlight.
I am reluctant to chop anything out of the garden, but I’m aware that the sooner this eyesore is gone, something more attractive can take its place. And, here is the problem.
My wife mentions that she feels trapped (not by me), with the view into the garden obscured by this large evergreen. And, it is. So, she will not be pleased when it is replaced, by anything, even such a marvelous choice as the Korean Sweetheart tree (Euscaphis japonica, below).
Today, the Sweetheart tree grows contentedly in a container on a patio, but of course, this was intended to be temporary. Sooner than later, the tree would grow too large, and though it will be a bit small from the start, I believe the Sweetheart tree is ideally suited to this spot in part shade. I expect the tree will not make much of an impact from the start, and no doubt my wife will learn to love it long before it grows to obstruct the open view into the garden.
The only open issue is, do I remove the tall Alaskan cedar, or bring someone in to do it for me? I am concerned about damaging the surrounding garden, both if I take the tree down and it falls on the house, or the nearby arbor, or if a crew comes in and stomps on tiny treasures scattered beneath the tree. There’s no good answer, but the least risky is to hire someone for this project and accept the possible losses.
Ramblin' through Dave's Garden 
I love your garden comments, and your wife is a sweetheart to put up with you! Your humor and affection for her are sweet! Can you address mosquito issues with the koi pond being in your garden. They eat bugs, but I’d think mosquitos would be a problem. Thanks.
I can tell you, the mosquitoes like her a lot more than me. I guess I’m also sour on the outside.
Wirh moving water, not much breeding can occur in the ponds, but there are areas of standing water in the garden, and a wetland on the back end. I spray an organic repellent that works reasonably well, bit less in areas with the densest foliage. The koi pond is protected by dozens of dragonflies, so it’s a good place to hang out.
More sunlight and sky would be an asset for a moment. Put the sweetheart tree in a neighbor’s garden when they are away for a few days.
My wife has suggested many times that I start planting on the neighbor’s instead of cramming more into this place.
The horticulturist who gave my colleague most of the stock plants for the rhododendrons that he grows did that. He lived on a compact suburban parcel in Menlo Park. When his garden space became insufficient for what he wanted to grow, probably back in the mid 1970s, he expanded into the garden space of adjacent homes. It was spectacular, but a bit excessive.
I would recommend Flournoy tree service. I have had them remove 3 trees over a period of 25 years and I have always been pleased by there tidiness as well as sensitivity to the surrounding plantings. However, no company is perfect, are they?.
Any time a tree in a neighbor’s yard was taken out (on purpose or through Mother Nature) it affected my plants around or near at least a little because of the change in the sunlight. Hope yours survived the change. (Never heard of a sweetheart tree before.)
One tree and several large limbs have come down in storms in recent years, bringing more light into an area of dense shade, with only positive results.