Modern pit mines for "hard rock" minerals, such as gold, silver, platinum, and copper, often cover hundreds of acres and descend hundreds of feet into the ground, generating waste dumps that extend to heights of several hundred feet and lengths of several football fields. These waste dumps often pollute surface and groundwater resources with toxic chemicals like cyanide and sulfuric acid, and heavy metals like arsenic and cadmium. Many hard rock mining sites are listed as hazardous waste sites under Superfund, with cleanup costs estimated in the billions of dollars. 

The Mining Law of 1872 allows owners of 20-acre mining claims access to an additional five acres of public land, known as a millsite claim, for processing mineral ore and dumping mine waste. In practice, however, the space required to dump the massive waste piles produced at many of today's hard rock mines exceeds the limits established by the Mining Law. For many years, the mining industry had been allowed an unlimited number of millsites for each mining claim. However, in the fall of 1997, the U.S. Department of Interior announced its intention to limit each mining claim to just one millsite. In the spring of 1999, for the first time the departments of Interior and Agriculture used the provision to deny permission for an open-pit cyanide-leach gold mine. 

In response, Senator Larry Craig (R-ID) introduced a rider to the Fiscal Year 2000 Interior appropriations bill that would have legalized unlimited mine waste dumping on public lands by eliminating the millsite provision (see House vote 7). 

During Senate floor consideration of the Interior appropriations bill, Senators Patty Murray (D-WA), Richard Durbin (D-IL), and John Kerry (D-MA) offered an amendment to remove the Craig language from the bill. On July 27, 1999, Senator Craig offered a motion to table (kill) the Murray amendment. The motion passed 55–41, leaving the Craig language intact. NO on the Craig motion to table is the pro-environment vote. 

In the final Omnibus appropriations bill for Fiscal Year 2000, the Craig rider was amended to allow enforcement of the single millsite provision for mines proposed after November 7, 1997. This would still exempt previously existing mines and mines proposed but not yet in production before November 7, 1997.