Modern mines for "hard rock" minerals, such as gold, silver, platinum, and copper, operate on a massive scale. Open pit mines 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. Mining waste sites are on the Superfund list of toxic clean up sites, and cleanup costs for these sites can run into the tens of millions of dollars. 

The Mining Law of 1872 permits each 20-acre mining claim to use up to five acres as a "millsite" for processing mineral ore and dumping mine waste. In practice, however, the space required to dump the massive waste piles produced by many of today's mines exceeds the limits established by the millsite provision. For many years, the federal government allowed mines on public lands to use an unlimited number of acres as millsites. However, in the fall of 1997 the U.S. Department of Interior announced its intention to resume limiting each 20-acre mining claim to a single 5-acre millsite. In the spring of 1999, the departments of Interior and Agriculture, for the first time, 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 Senate vote 1). 

During House consideration of the Interior appropriations bill, Representatives Nick Rahall (D-WV), Chris Shays (R-CT), and Jay Inslee (D-WA) offered an amendment to affirm the Department of Interior's interpretation and application of the Mining Law's millsite provision. The amendment was intended to preempt the Craig rider on the Senate version of the bill. The motion passed 273–151. July 14, 1999. YES is the pro-environment vote.