Probably common reed growing as a weed on that site. As you can see in the picture it spreads to take over large areas.

If not Phragmites then possibly Arundo - although I think that produces larger flower heads. Arundo is more clumping but is still a weed in California.

Bamboos display varying growth habits according to what kind they are, some grow as tight clumps that never send out runners. Check at some local outlets (independent garden centers instead of big box store plant departments) to see if these are possible in your area.

That is Arundo donax, I believe, and it is every bit as noxious and invasive as bamboo, if not more so. Spreads rapidly and incorrigibly by rhizomes and is a major ecological detriment to wetlands. I would not ever plant it deliberately.

Here is a link that might be useful: Arundo donax

Yes, I think the foliage looks generally more like Arundo also - what I was talking about is the same thing it says on the page you linked to:

It produces erect, terminal dense plumes of whorled stemmed flowers, with the clusters to 39 inches long

Phragmites tends to have a looser, more open flower head than showing in the photo, bboy, I think, but would be the same sort of obnoxious thing.

Wow! Thank you so much for your help. I'm glad I decided to post. It looks like I won't entertain Arundo donax for what I'm looking for. I will continue my search for a plant/tree that provides privacy but is not evasive.

There ARE bamboos that aren't spreading nightmares. They tend to cost more than the runners. :) But look for a nice clumping bamboo and then triple check the ID before you plant it. Clumping bamboos behave quite well.