It is probably a valley oak (Quercus lobata) or the closely related Oregon white oak. I love it too, and have planted one in the field near my house. It is one of my favorite trees.

Rosefolly

Here is a link that might be useful: Valley oak

Look out for the acorns when they mature later in the summer:

Long and slender (3-6cm long) = Quercus lobata.
Shorter and broader (2.5-3cm long) = Quercus garryana.

Age - very hard to judge, I'd make a guesstimate of 60-80 years.

Resin

My mom lives in Pleasanton (next to Livermore) and they've always called them valley oaks. I just love seeing them when I go out there.

rosefolly, thanks for the reply and this beautiful tree was one of the major reasons why we bought this lot to build on!

pineresin, I will look out for those acorns and thanks for posting the differences between those two species. Wow, 60-80 years...maybe if I ever need the services of an arborist, I will ask their opinion of age as well. I would imagine standing next to the tree, they'd be able to tell just by measuring and/or looking at the bark?

esh_ga, I'm actually right near the Pleasanton border (just on the other side of Vineyard past Ysabel) and you're right, I've frequently heard about valley oaks out here, but I just wanted to ask the experts at GW because I hadn't asked anyone specifically what this tree was (and since it's a vacant lot right now, I wouldn't feel right dragging someone out just to look at a tree and ask their opinion!)

My mom is off Bernal and she has one in her backyard (the house was already built when they bought it). My understanding is that you are "obligated" to do no harm to the tree and to ensure that you do what you can to continue it's survival. In their case, they have had professional arborist advice since day 2 and have had several deep root feedings applied. They also used their advice when it came to designing the landscaping in the back yard (decks, terraces, irrigation, etc). to make sure that they were not creating designs that would harm the tree. There are potential fines involved if the tree dies. This is the City of Pleasanton that mandated these conditions, so Livermore may be different.

They are magnificent trees and you are lucky to have one. Good luck.

A thing of beauty.

Hope the property is large enough that no harm will come to it in the building process, and that the tree's shedding, branch, leaf and acorn dropping will cause no problems for those who spend time on the property.

Then again be sure to properly shield and ground anything you build on the property as the root system of that massive tree must be a wide spreading potential network for electric charges to flare through from the ground and travel up the tree as lightening bolt type charges during some strong and highly charged, weather event storms.

I'd judge closer to 100 yrs for a valley oak this size and crown spread. The tree's habit, with big drooping limbs almost on the ground, are a trademark of valley oak. Oregon white is much more of a narrow-crowned tree that grows up more than out.

They can always mail the acorns to me if they become a problem. I'll gladly accept 'em. :)

esh_ga, I would imagine the City of Livermore probably has the same rules, but I never asked because I WANT to do the best I can for the tree, anyway! :)

This tree is actually at the entrance of our property, so we won't have any issues with landscaping design (we'll just remove the weeds and lay some bark underneath and around it).

Don't worry, katrina1, our homesite is 2 acres with easy access, so there is plenty of room to build without even going near the tree...and I have absolutely no problem with the tree's shedding and acorn dropping!

I appreciate your input on the tree's age, pinetree30, and I'll be excited to finally know the age from an arborist!

quercus_macrocarpa, that's funny about mailing you the acorns! Have you found a use for them or maybe a way to incorporate them somehow in your decor? They might make great vase fillers...I can't wait to live there and come up with a creative use for them! If I can't think of any, maybe I will need your address. :)

Looks like a Garry oak to me.

The most important things to remember are that (1) the roots will extend well beyond the edge of the crown, quite likely up to 1½ times as far as the branches, and (2) that oaks are very sensitive to soil compaction, and to changes in the soil level and water regime in their rooting zone.

So when building, put up a secure fence around the tree to protect its roots from damage by heavy construction machinery, don't change the soil levels in any landscaping, and don't irrigate it in the summer.

Yep, it all sounds rather officious, but it is the best for the tree!

Resin

"quercus_macrocarpa, that's funny about mailing you the acorns! Have you found a use for them or maybe a way to incorporate them somehow in your decor?"

I reckon he wants them for planting in his garden ;-)

Always looking to grow more oak species, especially white oaks.