From  Spiral Jetty - Utah
http://www.citysearchslc.com/E/V/SLCUT/0008/04/20/cs1.html

Salt Lake's answer to Christo, Robert Smithson, husband of Nancy Holt (see "Sun Tunnels") created the "Spiral Jetty." The Jetty is a 1,500 foot snail-coil of rocks, mud, and salt crystals that was tractored around near the northern shore of the Great Salt Lake in 1973 by Smithson and a heavy-duty construction crew. It's often submerged beneath the water, depending on how full the lake is, but you can call
                  the Golden Spike Historical Site (801-471-2209) and ask them if it's igh and dry--and also request a map, because the road to the Jetty is an exercise in navigation. --Stefene Russell

Spiral Jetty information in Salt Lake City: (435)471-2209

Driving directions:  From Interstate 15, take exit 368, head west on Highways 13 & 83 through Corrine and past the Morton-Thiokol plant.
 

A picture of the partially-submerged jetty at
 SpiralJetty by Robert Smithson, 1971. Rozel Point, Great Salt Lake 
http://www.mines.utah.edu/geology/utahgeo/UtahGIFS/SpiralJetty.html
 

Smithson bulletin board at:
 CLIP: Robert Smithson
http://www.clr.utoronto.ca/WB/CLIP.Smith/webboard.html