Thanks for all the advice. It sounds like the tree is doing ok then.

Anyone know how much water is too much?
I water it twice a day for about 20 minutes at a slow trickle (on the
same timer as my sprinkler in the front yard)

I recognize that it may one day be too big for the lot, but the trees
look so nice, and I do love walnuts (although hopfeully I will also
love them in 5 years, or however long it takes them to bear fruit.)

Thanks again
Ryan