I agree with ATH.
Here's a few suggested cut locations for a crown reduction just to give you an idea. The decision needs to be made by a trained arborist preferably using some type of man lift due to the spread out nature of the tree. Of course some climbers could do it with a rope and saddle and they would indeed be good climbers.
Over time another crown reduction would be nice..
A point: The removal of lower limbs on this walnut has forced growth out near the tips where weight and sail are leveraged. Interior limbs are good but are often removed unnecessarily.
Info borrowed off of the internet:
- Reduction reduces the size of a tree, often for utility line clearance. Reducing a tree’s height or spread is best accomplished by pruning back the leaders and branch terminals to secondary branches that are large enough to assume the terminal roles (at least one-third the diameter of the cut stem). Compared to topping, reduction helps maintain the tree’s form and structural integrity.
What is retrenchment in trees?
Retrenchment will involve tip pruning over several cycles,
to promote lower growth before any weight reduction is possible. Successive pruning restores light to the lower crown and manipulates apical control to allow shoots to develop into limbs, over several decades.
View attachment 962745