
The problem, which we know well but which maybe he might not have known then, is that the Lake's water level varies. At the time the jetty was built, the Lake elevation stood at 4195 feet, leaving it standing proud by 2 feet. But the elevation since the mid-70s has been around 4198-4200 feet or more, and as such the jetty has been underwater for most of its inanimate, magical life.
It disappeared. Gone. Inaccessible. All that work - and then nothing. Nothing but little waves, the wind over the shore, and the water.
Extremely. Salt. Water. Much saltier than the sea.

Whenever I post anything like this, half the readers here either skip the post, or they go "yeah, nice" and don't say anything, or, if they're Giles, they say "That's shit". ;o) Certainly my friend Chris would marvel at the millions spent on Spiral Jetty's construction and opine: "That could have paid for (x) hospital beds". After thinking about it for a while, I don't see the Jetty as being a statement, or useful (because it spirals inwards, nothing could moor there, even if your boat was immune to the clinging salt) in any way.
The point isn't that you could buy hospital beds or blankets for third-world children. The point is: no point. A massive fragile spiral. A jetty which leads you nowhere. Sometimes invisible. Newly, whitely reborn. Under dead water. In very nearly the middle of nowhere. If you're not convinced by now, you never will be, so go enjoy whatever you do enjoy. *sweet smile* Meanwhile, I'll enjoy my dreams of a future trip...
(*) I just reckon that Mr Smithson thought it would be a good way of inviting people to share in something he enjoyed, the beauty of a barren landscape, and maybe, if they were so inclined, the philosopy of it all. People are still making the pilgrimage along a nearly impassable road to walk along this Jetty. Artists have always thrived on that: new thought through attraction to new object. People always flock to see things that are visible from space.