Did you try and look up suitable trees for your area like county extension websites?

Sounds like really tough conditions. Are there any trees growing around you that you like the look of that are the right size?

I wonder if any of the Southwestern evergreen oaks would do well for you, like 'Canyon Live Oak' (Quercus chrysolepis), or perhaps a Mohr Oak (Quercus mohriana) or even the Silverleaf Oak (Quercus hypoleucoides), although it can get rather large.

You would need to protect any of these from animals when the tree is young, like wrap chicken wire around it.

There are a few different maples and aspens in other yards but I didn't think the roots would be good for our situation. There are plenty of apple and cherry trees, red leaf plums, peppers, oaks (although they're too large), and others I haven't identified yet.

My husband really likes the red leaf plum trees he has seen. But those willl attract bees in the spring, right? Is there something along those lines that doesn't flower?

I haven't found any county websites. . . .

I know they are not the best for shade, but aren't there several pines that grow well in that part of the country?

2007 edition of Sunset WESTERN GARDEN BOOK (Sunset Publishing, Menlo Park) has section on garden and patio trees in the plant selection guide near the front. Probably a good candidate for you there.

Red leaf plums are not long-lived. If you get one plan on removing it within 10-20 years. With that in mind, they are OK trees.

Here on the west coast they can be expected to last longer than that, which is nothing for a tree. Full size will not even be achieved in 10-20 years.

Roots can extend outward about 2 to 3 times the distance from the trunk that the canopy does, it is said. So if your 15 foot specification is based on the septic tank distance, consider that.

I believe I read an online article on a 'Thundercloud' purple-leaf plum chronicling a woman's experience with it, and I think it produced that sticky crud due to aphids on things underneath; might want to check whether that's a common problem.

I'd almost be leery of most anything 'maple' near a septic tank.

When you say a taller tree is okay if it doesn't get over 15' wide, are you walking radius (from the trunk) or diameter (of the whole canopy)?

Richard.

I mean the whole diameter of the canopy. I wasn't considering the roots though - I hadn't found anything on how roots generally space out.

I guess I was just hoping to get away from the 100s of pines and have something a little different in the yard. There are many other trees around town too, but they all seem to get so big.

American Hornbeam?

Becky,
I don't know if you are coming back to this thread or not, but I would suggest you go to the mall and look around at the trees they plant in the parking lot.
I'm serious, they are the perfect trees for your situation.
See how tall they are and try to take pics and come back for an ID of them here.
They can't have invasive root systems to be in a parking lot, and they provide shade.
Just a suggestion.

oooh, good idea! i have actually been eyeing a couple at the grocery store. i'll have to take some pictures when i go back. although the store is a bit lower in elevation and doesn't get as cold, it can't be too much difference . . .

"I don't know if you are coming back to this thread or not, but I would suggest you go to the mall and look around at the trees they plant in the parking lot."

I'd follow up online & research the species I saw.

Just because you see a tree on a 'tree island' in a parking lot doesn't mean that species is appropriate for that location.

Now, if the tree's been there many years, is roughly full-sized, looks healthy & right for your purposes, that might be good.

But an 8 - 10' tall juvenile of a tree that can hit 50'+ might not be such a good match.

Richard.

I just noticed that our little hardware store in town got some new trees. They usually only sell things native or very good for our area - which probably explains their small variety. Anyway, the ones they have right now are:

Purple Robe Locust
Goldenchain
White Alder
Krauter Flowering Plum

. . . and some cherry and apple trees.

I've looked a little at these online and I know some get too big. Haven't done enough research to know which, if any, would work for us. But looking at these, does anything similar pop into anyone's head to give us more options?

Oaks wouldn't be any good that close to the septic. They would get root rot. I did a lot of research and asking the right people when I was considering an oak for my yard. Stupid old cesspool!

I would steer clear of the locust. Brittle, short-lived and weedy. Alders get big and are prone to attack by bark beetles and again tend to be short-lived. The goldenchain looks like it would be a good candidate but all parts of it are poisonous. Would anyone who uses the playset be prone to putting plant material in their mouth?

The flowering plum looks like the best candidate.

Some other choices :
Mexican Plum - drought resistant, long-lived, leaves turn orangish in fall, Z6-9, 15-25' tall. This is a wild plum tree that is often used for rootstock. It makes a nice small tree on its own. White flowers in spring.
Domesticated Pear tree - to 20-25', very long-lived and you get pears, nice shape to the tree
Flowering crab-apple - tend to be fairly tough trees to about 25'.

How about a citrus tree? They don't need much watering once established, and require good drainage. I have one close to my house, so roots seem rather non-invasive. Also, You can prune the trees to the shape you want. I have mine like an umbrella. The only problem is the thorns.... with kids.... maybe you can get a variety without thorns....and citrus trees are evergreens. Another might be a pineapple guava. Again, you can shape by pruning. Now, I need one without fruit.... any suggestions out there? I have a spot that is close to our roof gutters --- and don't want fruit dropping into them... and again, it must have non-invasive roots.