A number of commuter rail, levee, and roadway construction projects from have come to a grinding halt in recent years because of federal law protecting archaeological resources. Part of the problem is the murky nature of historical preservation law, centered on federal requirements under section 106 of the National Historic Preservation Act of 1966 (NHPA) and its amendments. Although section 106 of the NHPA ostensibly covers only federal activities, most development, rehabilitation, and demolition projects of any size require a section 106 review. Any property listed in or eligible to be listed in the National Register of Historic Places is considered historic for purposes of section 106. The federal agency responsible for an undertaking must identify any historic properties, conduct a preliminary review, and from this review determine what types of surveys or field studies may be required and carry them out. In certain situations, contractors may prefer to have an archaeologist on-site during construction and forgo preliminary surveys. During the second phase of the review, the agency determines whether the undertaking will have any adverse effects. If the undertaking will result in any adverse effects, consultation with the state historic preservation officer and others is conducted to explore ways of avoiding or lessening these effects. This process should result in a memorandum of agreement, which outlines measures that the agency and contractor will take to reduce, avoid, or mitigate the adverse effects.