ARTINFO.com reports that "the Utah Division of Oil, Gas, & Mining has refused a request from the Pearl Montana Exploration company to drill for oil near Robert Smithson's earthwork sculpture Spiral Jetty, constructed in 1970. In a letter from the State of Utah's Department of Natural Resources to the company, obtained by the community group the Friends of Great Salt Lake, it states inadequacies in the application and notes, 'The prospect of drilling in the lake requires more than the usual attention to the sensitivities of the site.'"
If you're interested in this issue, a young man named Serge Paul runs a terrific blog called Spiral Jetty vs. Oilzilla. Kirk Johnson also wrote about the issue in the New York Times a few months ago.
(In the interests of full disclosure, I should mention that Smithson's widow, Nancy Holt, is a client.)